MOTUnation.com

I'm not sure how the concept works nor do I know what the benefits are and would like to understand...

I've looked all over the net for an explanation but haven't found anything.

A bus is simply a conduit for signal. Busses allow one to route signal to multiple destinations, create submixes and effects sends... the list is long. If you understand how a multi-bus analog mixer works, you'll get it. Try reviewing the manual from something like a Mackie 8-Bus console. I don't have the time to go into more depth at this moment, but you'll get it with some reading, I'm sure.

HC is right. Even though Mackie is far from my preferred mixer brand, they have an excellent mixer guide that is deliberately written as a general mixer tutorial and isn't specific to their mixer line or any particular model or model year.

I have a printed copy, which used to be handed out in retail music stores for free. Likely they have a PDF at their website that you can find. It really does a good job of describing mixer basics, and I found that I learned rather quickly from it.

Another option is to go to Yamaha's site and search for a manual on one of their MG-series mixers, as they too do an excellent job of covering the basics without being too specific to their own line of mixers.