Okay kiddo, let's talk about the mixolydian mode. Imagine you have a toy piano with 7 different keys, and you want to play a song. You start playing the first key, then the second, then the third...and so on. That's called the major scale.
The mixolydian mode is a little different. It's like playing the same 7 keys, but starting on a different one. Instead of starting on the first key, you start on the 5th key. So it goes like this: 5th key, 6th key, 7th key, 1st key, 2nd key, 3rd key, 4th key.
Why is this important? Well, it gives a different feeling to the song you're playing. It sounds kind of happy but also a little sad at the same time. It's used a lot in blues and rock music to give it that cool sound.
So if you ever want to try playing a song in mixolydian mode, just remember to start on the 5th key and play the same 7 keys as the major scale. Cool, huh?