Do you know what are chords?? Chords are 3-4 notes played together. Of course, they are not any random notes, but specific ones and those that create proper sounds for example C-sharp chord, etc.
In some case, channels can behave like chords. For example, if there are 4 channels of the same instrument playing at the same time, it will sound like a chord. If channels are different instruments, it won't sound like sound like a chord.
Hope your basics are clear
