There are three Hours: Eunomia (Harmony), Dyke (Justice) and Eirene (Peace).
The Hours assist the Olympians by organizing the Seasons and adding balance to Nature.
Their personal relations to the other immortals is only partially revealed, but in The Iliad, we see them personally attending Hera and her horses. They open the sky and Hera zooms from her home on Olympos to (Mount) Ida (Iliad 5.749) to distract Zeus from the battle for Troy.
The Hours guard Olympos with a dark veil and open and close the gates of the sky for the other immortals as they travel to and from their domains. Their charge is the vast sky and Olympous.