A speaker remembers a childlike wish: to pull the moon out of the sky and keep it, simply because it looked pretty. The reaching and the repeated failed attempts ("I tried and I tried") are told in a simple, almost playful way, which makes the wish feel innocent rather than greedy.
The turn comes in the last two lines. After all that effort, the speaker realises that you don't have to hold something to see its true beauty. The moon was always beautiful from where it was, and owning it was never the point. The poem suggests a quiet kind of growing up, from wanting to possess things to simply appreciating them.
The mood is gentle and reflective, with a little wistfulness at the start and calm acceptance at the end. The plain language and short lines fit the lesson: nothing complicated, just a small, honest discovery. Readers might also take the moon as a stand-in for anything we admire but can't have.