Someone on holiday is trying hard not to think about work, and the poem catches that effort in just six short lines. The office is described as "a reproach," as if it were a person quietly judging the speaker for being away. The speaker's answer is to "block out" the thought, which suggests a little guilt and a deliberate act of will. Relaxing isn't coming naturally here.
The second stanza shifts the picture. From far away, the office looks "so different," and the comparison to "a laugh in the night" is wonderfully odd. A laugh heard in the dark is sudden, a bit mysterious, and hard to place. It might be friendly or mocking, and distance has stripped away its context. The comparison hints that the workplace, once seen from afar, becomes strange and almost unreal.
The mood is quiet, wry, and slightly uneasy. The speaker has found some peace, but the poem leaves a faint echo of that laughter hanging in the air.