Well, it's an advertising buzzword at this point, because the word "system" sounds efficient.

But usually what those coaches mean by it is that they help small businesses streamline their lead generation by teaching them how to put in place automated marketing and sales processes – usually involving content marketing, email sequences/drip marketing, automated webinars, and other tools that don't require full-time human attention and help populate a sales pipeline.

It's not a bad word per se, but do always check what their "system" is based on, just to make sure that all you get isn't obvious information that you could have gotten for free.