Four short lines, and they turn the mole into a kind of philosopher. The speaker says the mole's "business," its job or duty, is to face "the dark / bruise of home" and "not take wing." That phrase is the heart of the poem. Home is pictured as a bruise: dark, tender, maybe painful, yet still home. The mole doesn't escape it by flying off, as a bird might.
The title, "Moleish," hints that the speaker wants to be a little like the mole, or already feels a bit like one. Judging by the wording, the poem suggests a quiet acceptance, even a stubborn kind of courage. Staying put and looking directly at what hurts is treated as work worth doing, not as failure.
The mood is hushed, earthy and slightly sombre, but not hopeless. There's dignity in the plain, matter-of-fact tone. The poem seems to say that some of us are built for staying, and that this has its own strength.