This code can only be redeemed once, if the code has already been used you'll have to buy a new Online Pass for $10.
If the code has already been redeemed (i.e. if you bought the game used) additional Online Passes will be available for (you guessed it!) ten dollars. Each game will include a seven-day free trial.Source: Joystiq
The online services under the Online Pass vary by game, but an EA rep told us they can include basic online multiplayer, as well as group/league features, roster and playbook updates, downloads of user-created content (like Photo Game Faces) and tournament support.