Phoebe: We went to a self-defence class today.
Rachael: Yeah, kicking a guy in the crotch all morning, really takes it out of ya!
In Friends, the drama, I saw these sentances but I couldn't understand what 'takes it out of you' means.
In dictanary, it means 'exhausted'. But I don't know why there is the word 'you' in last of the sentance.
I think exhausted person should be 'me' because Rachael learned the class and it might be made her exhausted.
Why there is 'you' in the last?
As pointed out by @WS2, the idiom take it out of refers to an activity that makes you very tired or requires a lot of effort:
Playing tennis in this heat really takes it out of you.
(http://www.macmillandictionary.com/dictionary/british/take-out)
The you in Rachel's sentence is generic. It refers to people in general:
In English grammar and in particular in casual English, generic you, impersonal you or indefinite you is the pronoun you in its use in referring to an unspecified person, as opposed to its use as the second person pronoun.
(https://en.wikipedia.org/wiki/Generic_you)
Rachel means this activity would make anyone tired.
