It's Parlez-vous français ? Vous parlez français.

Yeah agree with Stephanie. Actually I used to have the same question with you and asked my French friend, she said both are correct. I tried this during my trip to Paris,only changed into 'parlez vous anglais?' and everyone could understand~

Parlez-vous français? It can be used both in written and spoken language. In spoken language you can also say: Vous parlez français? with a rising intonation. France refers to the country, not the language or the people.