Here's a breakdown of the sentence:
* Pourquoi: Why
* est-ce que: This is a common way to introduce questions in French. It literally means "is it that," but it functions like "do" or "does" in English.
* tu: you (informal, singular)
* parles: speak (present tense, second person singular)
* français: French
Let me know if you have any other French sentences you'd like translated!