Okay kiddo, so you know how when we sing happy birthday or twinkle twinkle little star, we all sing together and our voices sound good together? That's called harmony, when different people sing different notes that sound good together.
Now, in Africa a long long time ago, people would make music too. But they didn't have instruments like we do now. They used their voices and sometimes some drums or other things they could find.
The music they made was different from the music we're used to hearing now. They used something called polyphony. Polyphony means singing or playing different melodies (that means different tunes or musical lines) at the same time.
So when people sang together, they would each sing their own melody but they would all sound good together. They didn't have sheet music or anything like that, they just knew how to do it because they grew up listening to that kind of music.
It was really cool because the music would have a lot of different layers and it would sound kind of like a big puzzle where all the pieces fit together perfectly.
Does that make sense, kiddo?