Okay kiddo, do you know what singing is? It's when we use our voices to make music. Well, trill is a fancy way to sing or play a musical instrument that involves quickly moving between two different notes that are very close together.
It's like if you have two stairs that are very close to each other, you can quickly jump from one stair to the other and back again. In music, it's called a trill when we do that with two notes that are really close to each other. It sounds like a little flutter or shake in the music.
It might be hard to do at first, but with practice and a lot of patience, we can learn how to trill and make beautiful music. And that's what trill is all about, being fancy and making our music even more special!