Send & Return on my mixer

what do these actually do?

Broadly speaking a send will send audio out to a certain source.

The return accepts audio back into a source.

You can choose which channels to send in most situations.

An example would be the FX return fader on many mixing desks. You start by sending the audio you want processed by the FX module. The FX return fader then returns the processed audio with reverb or echo added.

You could also use sends for a mix minus podcasting setup. You send only the audio a podcast guest needs to hear (like your microphone and the podcast jingles but not the channel with the guest speaking). The final mix would includes all the channels.

I will keep re-reading this @Mike. Trying to grasp what realistic use it would be for me and if I could use it…if there is any chance a quick 5mins on a stream, that would help ever so much…