I haven't played FIFA in a long time (about 5 years now) and I recently found out that you're able to get player cards. The question is, what are those cards used for and what exactly are they?
Fifa Ultimate Team. You can read more about the 2016 version here: https://www.easports.com/fifa/ultimate-team/features
Basically you build a squad of cards for playing against people online. There are different levels of cards including bronze, silver, gold, and special Team of the Week/Team of the Year cards that give stat boosts to players. In addition to player cards, there are also manager, contract and item cards that you use to keep your team together and healthy.