Here the speaker describes being stuck in a cage so small that their back is pressed to the wall and their feet are jammed against the side. The cage is most likely a metaphor rather than a literal place. Judging by the line about "the demons in my mind," it points to inner struggle, perhaps anxiety, depression, or some other private pain that makes the speaker feel confined.
What hurts most is not only the trapped feeling but the silence around it. "No one notices" and "still no one knows" frame the poem, so loneliness is repeated right to the end. The speaker even calls themselves "a freak on the show," as if their suffering is on display yet nobody truly sees it, or as if they feel judged and strange.
The short, plain lines create a tense, claustrophobic mood. There is little space on the page, just as there is little space in the box. The tone is quiet, heavy, and hopeless, like a cry nobody hears.