How do you say what are doing in French language?

There are a few ways to say "what are you doing" in French, depending on the context and formality:

Formal:

* Que faites-vous? (This is the most formal and polite way to ask)

Informal:

* Qu'est-ce que tu fais? (This is the most common and casual way to ask)

* Tu fais quoi? (This is a more informal and slangy way to ask)

In the present continuous tense:

* Que fais-tu en ce moment? (What are you doing *at this moment*?)

It's important to choose the right expression based on who you are talking to and the situation.