In just a few lines, a small, ordinary creature, the clothes moth, becomes something closer to a storyteller or a musician. The speaker imagines her telling "stories" to the closet, as if her tiny movements in the dark were a kind of speech. Then the poem shifts to music: her body is "her instrument," full "as a white bell." The comparison makes sense visually, since the moth is pale and rounded, and it turns something we usually see as a household pest into something delicate and almost beautiful.
The last two lines widen the view. Out "in the void," another bell rings, which suggests an answer, or a kind of kinship, reaching beyond the closet. The poem doesn't say what that second sound is, and that openness is part of its charm. The speaker seems quietly fascinated rather than annoyed, and the mood is hushed, curious, and a little wondering, as though a tiny corner of the house had briefly opened onto something much larger.