Three short lines give us a simple scene: someone walking by themselves, at night, along a high ridge. The first two lines set the place and the solitude. Then the last line surprises us. Instead of describing the view or the sky, the speaker turns attention to their own body: "my quiet hips."
That small detail does a lot. Hips are what carry us when we walk, usually unnoticed, and calling them "quiet" suggests a smooth, easy, unhurried stride. It also hints that the speaker is deeply at ease, so tuned in to the walk that the body seems to move without effort or noise. In the dark, with sight limited, other senses and physical awareness take over.
The mood is calm, private, and a little mysterious. There's no sign of fear, even though the speaker is alone in the dark. Instead the poem feels peaceful, like a moment of being completely present in one's own body and the quiet night around it.