Six short lines hold a whole love story, and it lasts only one night. The speaker "had" someone at sunset and "lost" them at dawn. Nothing else is said about who the person was or why they left, and that silence is part of the effect. The speaker doesn't explain or complain. They just set the two moments side by side.
The title, "Beach Please," suggests a seaside setting, and the poem's timing fits it: the light fading at the start, the light returning at the end. Sunset usually feels warm and romantic, while dawn can feel cold and bare, so the day's shape mirrors the shape of the relationship. The word "you" gets its own line twice, which makes the other person feel both important and out of reach. The mood is wistful and a little stunned, as if the speaker is still working out how fast it all happened. The title's casual, almost joking tone may also hint at a speaker hiding hurt behind a shrug.