What does ab, aba, & rondo mean in music?

AB and ABA are called forms, the way a piece of music is organized. AB Is called binary form, like the cat is bad, the cat is good. ABA is called Ternary form, consisting of three sections, so like the cat is bad, the cat is good, the cat is sad. Rondo- a form of music where the musical material started in the beginning of the music keeps returning.