A person is getting dressed, laying out clothes for the day, and pauses to look at the money they have to spend. That small, ordinary moment is the whole poem, and it carries a quiet weight. The speaker isn't panicking or complaining. They simply stand and look, and the stillness of that looking says a lot.
The final image is the key. Money that is "dry as rust" feels brittle, old and used up. Rust is what happens to metal left to decay, so the comparison suggests the money is scarce, perhaps coins, and that it offers little comfort. Calling it "this day's money" also makes it feel like a daily ration, something that has to be stretched until evening.
The mood is hushed, tired and resigned. The short lines and plain wording mirror the speaker's limited means, and the poem leaves us to imagine the worry beneath the calm surface.