In just three short lines, the poem gives us a small, quiet scene: someone sits alone on cold stairs, going back over a piece of writing one more time. The title tells us this is proofreading, the careful, slightly tedious work of hunting for mistakes.
The odd detail is the last one. The speaker reads "with my left eye." It's a strange, specific thing to say. Maybe the speaker is tired, maybe the other eye is closed or covered, or maybe it's simply a wry way of showing how little attention is left. The poem doesn't explain, and that gap is part of its charm.
The mood is hushed, a bit chilly, and gently humorous. The cold stairs suggest an in-between place, not a desk, not a proper room, which makes the task feel private and slightly worn out. We sense patience, fatigue, and perhaps a little self-mockery, all in a very small space.