Hey kiddo! So, you know when you listen to music and sometimes you hear different songs mixed together? That's called a medley!
It's like when you have a bunch of toys, like your dolls and blocks and balls, and you play with them all at the same time. A medley is like that, but with songs instead of toys.
Sometimes in a medley, the singer or band will sing one part of a song and then switch to another part of a different song. It's like when you read a book and switch to a different book halfway through, but it still makes sense.
They do this to make the music more interesting and fun to listen to. It's like when you make a silly face and then make another silly face - it's more fun than just making one face over and over!
So that's what a medley is! A bunch of songs mixed together to make one cool song.