Are:
* Our: This is a possessive pronoun, meaning belonging to us.
* Hour: This is a unit of time.
Whose:
* Who's: This is a contraction of "who is" or "who has".
Let's look at some examples:
* Are you going to the party? (verb)
* Our car is in the garage. (possessive pronoun)
* We have one hour left. (unit of time)
* Whose book is this? (possessive pronoun)
* Who's coming to dinner tonight? (contraction)