Eli Manning was talking about some of his favorite passes to throw when, naturally, he mentioned how gifted Odell Beckham Jr. is at turning something small into something quite big.

“It’s usually completed at about 9 or 10 yards, a lot of times Odell catches that,’’ Manning said Tuesday morning to an assemblage of high school quarterbacks and receivers at Wayne Valley (N.J.) High School. “This year hopefully Brandon catches that and takes it for about 60 yards. Throw it short, let ‘em run deep, I like that.’’

Brandon Marshall, standing alongside his new passer with the Giants, chuckled.

“I can assure you I’m not taking it 60, 70 yards,’’ Marshall said at the AIRO 7v7 New Jersey North Football Event on behalf of the Gatorade Beat the Heat program. “I’m just gonna take it 10 yards, move the chains and let Odell take it the 60, 70.’’

When the youngsters began playing a series of 7-on-7 games, Marshall — entering his 12th NFL season for his fifth different team — went on to reveal how much of an adjustment he had this spring, learning where and when Manning is going to throw and place the ball.

“I think I dropped every other ball the first two weeks,’’ Marshall said, laughing. “I was like, ‘These guys probably think they made a bad investment.’’’

There was more of this.

“I think our last practice Eli just threw it at my feet and said, ‘I’m just gonna throw it so you get the timing — I’m just gonna do my job and you got to do yours,’ ’’ Marshall said.

This all sounds like a setup. Sure, Marshall at 33 years old might not be the monster receiving target he was 10 or even five years ago. But this is a guy who wreaked havoc on the league for the Jets in 2015, with 109 catches for career highs in yards (1,502) and touchdowns (14). The Giants gave him a two-year, $11 million contract. Though they do not expect him to match Beckham’s production, Marshall is soft-selling what he can do for the offense.

Asked if Marshall is sandbagging just a bit, Manning smiled and told The Post: “No doubt. He’s humble. He has the ability to make big plays and get down the field. He’s not a 4.3 40 guy, that’s not why we brought him in. We brought him in because he’s a big target, great in the red zone, but he also – hey, I hit him on go-routes this offseason, he ran by defenders. He has the ability to make all the plays, run all the routes and make big plays for us.’’

With Beckham, Sterling Shepard entering his second NFL season and rookie tight end Evan Engram, the first-round draft pick, Marshall does not have to make all the big plays for the Giants. He is certainly capable of making his share, though, and his trademark confidence has not waned one bit.

“They were clear with me we have a No. 1 receiver that’s not even in his prime yet, and that we also have a freakin’ stud in Sterling Shepard, so there’s only one ball,’’ Marshall told The Post. “I want this to be my most efficient year. It may not be my best statistically, but when it comes to the standpoint of efficiency, I really want to dominate in that category.’’

The last time he was not the acknowledged No. 1 receiver on the roster, Marshall said, was back in 2006, when he was a rookie with the Broncos. He says he could be a No. 1 again, but not with the Giants.

“I know I could have gone to another team and caught 100-something balls and put up 1,500-1,600 yards, but that’s not the mission right now,’’ he said. “That’s not the goal. My goal is to touch that Lombardi Trophy. Sometimes you got to sacrifice. There’s gonna be times where I may think I’m open or may be open and not get the ball, and it might hurt. I understand I’m in a great place and the only thing that matters is bringing home that trophy.’’

Just the other day, Marshall did something quite unusual. He sent Manning a text message, requesting some FaceTime access to go over the signals and plays learned in the practice sessions the past two months.

“That’s one of the reasons we have a great opportunity, because everyone knows where they’re supposed to be and knows where the ball’s gonna be and when it’s coming,’’ Marshall said. “That’s something I never had to deal with my entire career. I never had a quarterback be so precise with his preparation and also just ball placement and getting the ball out quick. That’s been the biggest adjustment for me.’’