Okay kiddo, have you ever heard people singing together and some of them were singing the same thing while others were singing something different? That's called harmony!
Now, there are two types of harmony: close and open.
Close harmony is when the singers are singing notes that are really close together, like a group of bees buzzing where each note is only slightly different than the next. This makes the harmony sound tight and cozy, like a big hug.
Open harmony, on the other hand, is when the singers are singing notes that are farther away from each other, like a group of birds chirping where each note is really different from the others. This makes the harmony sound more spacious and airy, like a wide open field.
Does that make sense, kiddo?