you
The French word "vous" is a pronoun that is used to refer to the second person plural, or to a single person in a formal context. It is used in the same way as the English word "you". For example, "Comment allez-vous?" means "How are you?". In informal contexts, the singular "tu" is used instead of "vous".
Where did you go?
In French, 'Où êtes-vous allé?' is the formal or plural way to ask 'Where did you go?'. The verb 'être' in 'êtes-vous' is used as the auxiliary verb in compound tenses.
You have a nice hat.
In this sentence, 'Vous avez' is a phrase that means 'You have'. 'Un joli chapeau' stands for 'a nice hat'.