The poem starts with a small, cold scene: autumn wind, and the rattle of a rat moving about somewhere nearby. The word "bold" matters. The rat isn't hiding or startled. It acts as though the place belongs to it, which hints that the people inside have little power over their own space.
The second part, set apart from the first, turns from sound to statement. "Poverty grown so great" suggests things have been getting worse for some time, and the speaker has stopped hoping for more. Yet the last line, "we have just one another," holds two feelings at once. It sounds like loss, since nothing else is left, but it also sounds like closeness. Having each other may be the only comfort there is, and perhaps the only one that matters.
The mood is bare and quietly sad, with a thread of tenderness. The poem never complains loudly. It lets the wind, the rat and a plain admission carry the feeling, and that restraint makes it hit harder.