Be a Pro is a game mode in FIFA 09, FIFA 10 and FIFA 11, where the player either creates their own player or uses a professional players to play as over 4 seasons.
FIFA 09 added the functuality of a 10 vs 10 Be a Pro Online match.
The FIFA 09 Box quotes: "Playing as your favourite superstar or creating a player of your own, master a single position during a four-year campaign."