Ultimate Team is the most popular mode in these games, and is basically a huge metagame that involves you managing a team, and managing individual players.
Coins are the primary currency in Madden Ultimate Team – you use these to buy packs containing new players and upgrades. And while, sure, you can always just buy these coins with real world money, there are ways to maximize your net gain in game, too.
Normally, coins can be used to level up in Ultimate Team and upgrade players in Ultimate Team. To farm coins, you can try many methods: playing games online, participating in tournaments and Solo Challenges and Weekend Leagues, and using Auction House.