The poem sketches two cities layered on top of each other. The first is the one we can see, where something small and gentle has gone missing: bread for the swan on the water. It's an everyday kindness, and the poem treats its absence as a loss. The second city, "made of fear," is harder to pin down, but the speaker says it "begins to decay like mad," as if anxiety eats away at the place from within.
The last image is the loudest. The street curses "in 42 voices," a crowd too many and too scattered to be one person's complaint, and what they say is blunt: money is not to eat. Judging by the wording, the speaker hears hunger and frustration, and perhaps a sense that cash has failed the people who depend on it.
The mood is uneasy and bleak, but quietly so. The speaker doesn't lecture. They simply set a hungry swan beside a hungry street and let the contrast do the work.