Learn Italian: Vi preparate, vi vestite e uscite. - You all get ready, get dressed, and go out.

In Italian, getting ready (prepararsi) and getting dressed (vestirsi) are reflexive verbs. This means the action reflects back onto the subject. Because the subject here is 'you all' (voi), we use the reflexive pronoun vi (yourselves) right before the verbs. Literally, it means 'you prepare yourselves' and 'you dress yourselves.'

Why is there no vi before uscite?

Because going out (uscire) is not a reflexive verb. You get yourselves ready and dress yourselves, but you do not 'go out yourselves.' Therefore, uscite is just a normal verb and does not take a reflexive pronoun.

Where is the Italian word for 'you all' (voi) in this sentence?

It is dropped! In Italian, the verb endings (-ate and -ite) already tell us that the subject is voi (you all). The reflexive pronouns (vi) give us an extra clue, so adding voi at the very beginning isn't necessary unless you want to add special emphasis.

Why do the verbs have different endings (-ate vs -ite)?