You can use the question phrase, “À quelle heure est…?”
to ask what time something is. For example, if you want to know what
time breakfast is when you go to a hotel, you can ask this:
À quelle heure est le petit-déjeuner? – (At) what time is breakfast?
You literally have to say “at what time…” in French, even though, in English, we often simply just say “what time”
À quelle heure est la réservation? – (At) what time is the reservation?