In just three short lines, the speaker talks to a clock as if it were a person who is always rushing around. The title, "Slacker," gives the poem a playful twist: the one who wants to loosen up is the speaker, and the clock is the "busy" one, bustling along with its ticking and schedules.
What the speaker wants is simple. There is one particular hour they are longing for, and they ask that it might "finish" so that "us" can simply "be." The word "us" suggests the speaker is thinking of being with someone else, though the poem doesn't say who. There's a small puzzle here, too: the hour the speaker wants seems to be the one that would end the waiting, or perhaps end the pressure of time itself.
The mood is quiet, tender and a little wistful. It feels like a sigh, gentle rather than angry, with a wish to rest in a moment without being hurried along.