Learn French: Tu vois qui dans la voiture ? - Who do you see in the car?

In everyday spoken French, it is very common to keep the normal statement word order (subject + verb) and put the question word exactly where the answer would go. Instead of starting with 'who', you literally ask 'You see who?' (Tu vois qui ?).

Could I put qui at the beginning of the sentence if I wanted to?

Yes, but you would need to change the rest of the sentence. You would have to add extra words (Qui est-ce que tu vois...) or flip the verb and subject (Qui vois-tu...). The style shown here (Tu vois qui...) is the easiest and most natural way to ask this in casual conversation.

Wait, does qui mean who or what?

qui always means 'who' and is used for people. If you wanted to ask 'what' you see, referring to a thing, you would use quoi in this type of sentence: Tu vois quoi ?

Why does vois end in an 's' if Tu means just one person?

For almost all French verbs, an -s at the end is the standard ending that matches tu (you, singular). The verb here is voir (to see), and its tu form is tu vois.