The title points to a meditation practice where you imagine your own body as a corpse, and the poem reads like a few quick notes from that exercise. The speaker starts with a striking image: dancing on their own grave. They call it "a foolish and simple act," which sounds half embarrassed and half freeing. It's as if facing death head-on can only be done with a bit of silliness.
The middle lines are the strangest and most interesting. Meeting the body "in unmeeting it" suggests that by letting go of the usual idea of "my body," the speaker sees it more clearly for the first time. The last stanza pictures the body as something sent on a mission that it can't carry out, because a corpse can do nothing, "for all its great noise." That noise might be the clamor of the living ego, or of the world around us. The mood is quiet, wry, and a little unsettling, with humor sitting right beside the thought of death.