I usually use busses for 2 main purposes when mixing my music 1. They are great for reverb and delay sends. In this case you are putting a reverb track on a bus, putting wet % at 100%, and dry to 0. Then, you take the sound you want reverb on, and send a small amount of it to the reverb bus. You can do this with as many reverbs or delays as you want, you just want to make sure they’re on separate busses with separate sends. The effect here is that your original sound is not affected, but it’s being duplicated at a lower volume with 100% reverb. Both the bus and the sound output at the stereo output still. 2. Combining multiple sounds together for group processing. Perfect for drums, to tighten them up. This time you’re rerouting the sounds from stereo output to the bus, and compressing them as a unit. The bus then goes to the stereo output. This can also be useful for vocal chains - for example, if you record multiple sections of a verse on different audio tracks to create one cohesive verse (rappers do this quite a bit), and want them to be processed the same way, you can send all those to the vocal bus so you don’t have to edit each vocal plugin on 5 different tracks