It is often used in a question, like:
* "Que tu veux faire?" (What do you want to do?)
* "Que tu veux manger?" (What do you want to eat?)
It can also be used in a statement, like:
* "Fais ce que tu veux." (Do what you want.)
The phrase literally translates to "that you want," but in English, it's more natural to say "what you want."