It's not. It's a Federation of Associations. It's a bit like how the US is not country and a state together, but is a country made up of states.
Edit: If you're referring to the way that FIFA is short for Fédération Internationale de Football Association, then the answer is because it's in French. In French, the adjective comes after the noun, i.e. red ball is balle rouge (ball red). Thus, association football is football association. Therefore, FIFA is not 'The "International Federation of Football" Association', but International Federation of Association Football.