There is a piece of piano music called Square-O by Elissa Milne. I would like to know the meaning of it.
There are two answers to this question, whenever it is asked about any piece of art, be it music, sculpture, a novel, or whatever.
1) It means what it means to you.
2) It means what the author had in mind, and not all authors are willing to share that information.
There's a rondeau by Henry Purcell (ZT684), originally for the play Abdelazer, that was printed in some harpsichord collections with the title "Round-O". "Square-O" is probably a pun on that.