The speaker is alone, drifting through the day "from one thing to another" without much sense of purpose. The poem opens with a quiet admission of loneliness, then quickly turns to something harsher: the speaker feels like "a blank to be filled," an empty space waiting for something, or someone, to give it meaning.
The second stanza makes the feeling heavier. The speaker becomes a "stone prisoner," a body made of arms and openings, built mainly to take in "tired suppers." Eating is reduced to a dull routine, and the person seems to shrink into a machine for getting through the day. The last lines push this further. The hands "have / nothing to do / with hands," as if even the body's most useful parts no longer feel like the speaker's own.
The mood is flat, numb and a little bleak. The short lines and plain wording match that emptiness, leaving the reader with a sense of someone cut off from other people and from themselves.