The speaker describes a kind of collective transformation: "we" take the day and turn it into night, then look over what has changed. The list that follows is striking. War becomes opera, which makes something terrible into a staged spectacle. Streets become "dangerous doors," as if every ordinary route now leads somewhere risky or unknown. Blown sand, an image that suggests desert, wind, and perhaps a battlefield, becomes the word "Love."
Each change takes something harsh and gives it a form of beauty or meaning. But the last two lines complicate that. Dancing and singing, the speaker says, "would spoil the music." The music seems to need stillness, distance, or silence from the people it's about. The poem seems to ask whether beautifying suffering is a kind of comfort or a kind of betrayal.
The mood is cool, dreamlike, and uneasy. The speaker sounds calm, almost detached, which makes the poem's quiet unease more noticeable.