Three small details sit side by side here: the slow sound of a cello, the act of pushing a velvet armchair, and rain coming down outside. Nothing dramatic happens. The poem seems to catch an ordinary moment indoors, perhaps someone rearranging a room while music plays and the weather settles in.
The speaker never says how they feel, but the images do the work. "Slow" music, soft velvet and steady rain all share a gentle, heavy quality. Even the pushing of the chair, which could be a clumsy, noisy job, feels slowed down by the company of the cello. The word "as" in the last line links the actions together, so the rain seems to move in time with everything else.
The mood is quiet, cozy and a little wistful. It's the kind of afternoon when you stay inside, notice small things, and let the day move at its own pace. The poem asks you to do the same: read it slowly and listen.