Three short lines, and almost nothing else on the page. That bareness is part of the point: the poem feels as small and enclosed as the space it describes. The speaker is in a room, but calls it a "box," which makes it sound less like a home and more like something closed in and cramped, maybe even something you could be packed away in.
The key line is "no one can see me here." It could be read two ways. The speaker might feel safe, glad to be hidden. Or they might feel invisible and forgotten, shut away where nobody notices them. The title, "Lonely Room," nudges us toward the second reading, though the first may still linger underneath. Being unseen can be a relief and a hurt at once.
The mood is quiet, still, and a little sad. There's no outburst, just a flat, hushed statement, which makes the loneliness feel ordinary and heavy rather than dramatic.