The speaker describes a life split between a painful home and the open streets. Once old enough, they walk out alone and feel free for the first time, but they keep returning to a house where they are beaten and where they try, usually without success, to stop the fighting. The city becomes a refuge. Strangers are kind in small ways, like the woman who offers a sandwich, though even the drunken men and the courtyard music can't fully quiet the memory of violence at home, since loud noises bring it back.
The turning point comes on a rainy walk, when the speaker finds a discarded guitar. The word "sane" suggests how much this matters: after so much chaos, music gives them something steady. The mood moves from weary and bruised to quietly hopeful. The final line calls the guitar "a beginning," which leaves us with the sense that the speaker's story is only starting, and that something thrown away has become the thing that saves them.