"il" can be a masculine pronoun or an impersonal one ("it"). When we say "il est 5 heures" it's like "it is 5 o'clock". it's impersonal. It's the same for "il fait 15 degrées" (it's 15C). It's not masculine nor feminine, it's just "it".
Heure is feminine and "quel" conjugate with the word it belongs. So it can become "quelle" "quels" "quelles".