Two lines, and the whole poem turns on a swap. At noon, "Object" gives us "a piece of meat": something passive, inert, made to be handled or eaten. At night, the same thing becomes "a mouth": something that wants, speaks, bites, kisses, or hungers. The title suggests the subject is a body, possibly a person's, and the poem seems to say that body changes depending on the hour.
The poem never says who is speaking or how they feel, so the emotion has to be read between the lines. Judging by the flat, clipped wording, the tone is cool and almost clinical, yet what it describes is unsettling. Meat suggests a body reduced to a thing, while a mouth suggests appetite and desire. The shift from being consumed to consuming can feel threatening or erotic, or both. Daytime seems to strip the body of agency, and night gives it back a hunger. The mood is stark, uneasy, and a little darkly charged, and the gap between the two lines is where the tension sits.