How to say in French do you know French?

There are a couple of ways to say "Do you know French?" in French, depending on the context and the level of formality you want:

Formal:

* Parlez-vous français? (This is the most common and formal way to ask.)

Informal:

* Tu parles français? (You use this if you are speaking to someone you know well, like a friend or family member.)

* Vous parlez français? (This is a bit more formal than "tu parles français," but still considered informal compared to "parlez-vous français.")

Note:

* The verb "parler" means "to speak."

* "Français" is the adjective and noun for "French."

* "Tu" is the informal "you" used for one person.

* "Vous" is the formal "you" for one person, or the plural "you."

* "Parlez-vous" is the formal plural "do you speak" (used for one person or multiple people).

It's important to choose the right form of "you" depending on who you're talking to.