What is a play-down in association football?

Im 14 and my coach says that i have to be a play-down cuz im a 3rd year senior and he says that if i was 12 or 13 i wouldnt be one so what exactly is this rule|||lol association football is soccer http://en.wikipedia.org/wiki/Association鈥?/a> im sorrry i cant help you, it would of been smart to ask what play-down was to your coach.