ALTOONA, Pa. — Here’s what you need to know about Amed Rosario, the Mets shortstop of the near future.

— “He’s got lightning hands,’’ second baseman L.J. Mazzilli told The Post of his Double-A Binghamton teammate. “His bat path has gotten straight to the ball. Now he’s trusting how fast his hands are. He believes he can get to any pitch that’s inside.

“The other day I was on second base and the pitch was a little low and in, and he hit the ball off the 405 sign. Dead center. Most guys would have pulled that ball to the six-hole. He just stayed in on it, short, quick and it was easy pop at 20 years old. He’s putting all the tools together. Impressive.’’

— “He has soft hands and fluid action, he just makes everything look easy at shortstop,’’ said an NL scout who knows the Mets’ system inside and out, and had just watched Rosario play. “He’s got good instincts and he made a couple of plays you can’t teach. Offensively, he’s making key adjustments and that’s when you really know a kid is coming fast.’’

— “His approach has gotten a lot better, and that has allowed him to put up the numbers he did in [Class-A] St. Lucie in the first half and now with us here,’’ said Binghamton manager Pedro Lopez, a former catcher/first baseman who spent all 13 years of career in the minors and who takes great pride when his players make The Show. “He’s gotten on board with what we are trying to do as an organization, getting guys better, especially not swinging out of the strike zone as much.’’

— “Rosario, man, I’ve gotten to watch him grow and he definitely excelled at every part of his game the last three years,’’ said Binghamton first baseman Dom Smith, who is headed to the Futures Game next week in San Diego and is another player who has made great strides and will be at Citi Field before you know it. “He’s made some plays this year that have shocked me and excited me. He’s really growing into a great shortstop.’’

— And this from Jose Reyes, who knows a thing or two about being a top shortstop prospect in the Mets’ organization, when asked what his impressions of Rosario are after playing alongside him: “Wow! He’s 20 years old and he looks like a veteran.’’

Enough said.

Rosario has the “wow” factor and much more. He is 6-foot-2 and strong. The Mets signed him for $1.75 million in 2012 at the age of 16. He hit .309 at St. Lucie this season before being promoted. In his first eight games at Binghamton, Rosario was hitting .414 with a .469 on-base percentage, a .621 slugging percentage and 1.089 OPS.

He is applying what he is being taught, especially over the past year. If he continues to improve, perhaps he will be at Citi Field at some point next season, certainly in 2018.

Remember, he is just 20, having been born Nov. 20, 1995. Great strides are being made.

“I’ve been working on my concentration each and every time I go to home plate,’’ Rosario said through a translator.

Rosario started playing shortstop at the age of 12.

As for his first name, Amed, as he told The News Press in Fort Myers, Fla., in May, Rosario said his father gave him that name because it came from an Iranian soap-opera character his father enjoyed watching.

Growing up in the Dominican Republic, there were two shortstops Rosario admired, Jose Reyes and Hanley Ramirez.

“It’s a great honor to be able to play with Jose, I never thought I would have the opportunity to play with him,’’ Rosario said.

The veteran Reyes, who is learning third base, gave Rosario pointers at shortstop. But does Rosario smile as much as Reyes does on the field?

Rosario offered his big smile and said, “It’s possible.’’

Rosario is not trying to look too far ahead to Citi Field.

“To get there I need to keep working hard here, day by day,’’ he said. “When God gives me the opportunity, I will be there.’’

Reyes wants to make sure that Rosario understands what the major league challenge is going to be like and, most importantly, don’t get wowed by the hype.

To that end, on Rosario’s first night with Binghamton, Reyes and Juan Lagares took him out to dinner.

“We talked about a bunch of stuff, but the good thing is he asked questions,’’ Reyes said. “When you’re young and you are around veteran players and are asking questions, that’s what you want to see.

“Juan and I both told him: Don’t worry about being a top prospect. Come here every day and play hard, do your thing. Don’t worry about when you are going to be in the big leagues. You are going to be there in the big leagues [eventually]. Go out there and perform, hustle, run the bases hard — little stuff that people are always going to see.

“I was a very good prospect in the organization, and a couple of times they took me out of the game because I didn’t run the ball out hard,’’ Reyes said. “Even in the big leagues, one day Willie Randolph took me out of the game. That’s the little stuff you have to learn, and we told [Rosario]. People are always going to be looking at you. So don’t let anyone have to tell you, ‘You need to run hard. You need to hustle.’ Always come here with the same attitude, playing hard every day.

“Your time will come.’’

Reyes wanted to make one other point: “He’s a skinny guy, but he is strong.’’

Rosario’s adjustments are on display every night. After the opposing starting pitcher got an inside fastball past Rosario on this perfect night for baseball in Western Pennsylvania, the lefty tried to finish him off later in the count with the same pitch.

Those lightning hands Mazzilli mentioned were on display, and Rosario ripped a line drive down the left-field line for a double.

“Jose was quicker, but this kid has plus speed and can really run,’’ the scout said. “And he’s a bigger kid than Jose. What I really like most of all is that he is starting to make adjustments at the plate to breaking pitches. There are times early in a count, a guy may throw him a breaking ball or a changeup and he’s out on his front foot, and then the guy tries to throw the same pitch and the kid will hit it.’’

Rosario developed his baseball instincts the old-fashioned way. “Work, work, work,’’ he said. His favorite part of the game is hitting.

Asked what kind of player Mets fans will see when Rosario arrives at Citi Field, he said, “A humble person who plays the game for the fans and for happiness.’’

Noted Reyes, Mets shortstop of the past: “No doubt, the Mets have a shortstop for the future.’’

That future is coming fast.