Similar to the first Ultimate Vault Hunter Upgrade, this one also adds additional levels (as in player levels) to get more loot and fight tougher enemies. Be aware that you also need the Commander Lilith & the Fight for Sanctuary content pack to have access to all the features this DLC adds. I suggest you either play the base game first; once you decided you want this, keep in mind that the Game of the Year Edition of Borderlands 2 does not include this DLC, you would either need to buy it separately or go for the Borderlands 2 Complete Edition.