Businesses first considering BPM (and those still maturing) should understand that BPM offers them the opportunity to do almost anything. They can remove much repetitive work, eliminate specific components of work through automation, and orchestrate the flow of work between people for effectiveness.
BPM can also be used to create differentiation, like with supply chains and new product development.
BPM can be used to craft and control customer experiences, to intelligently nurture leads through the marketing and sales processes, and to find and implement that next big innovation.
BPM can be used to promote employee satisfaction and the desired company culture.
The reason why it can do all of these things is that the majority of our time is spent performing work within multiple processes. Saying it a different way, we can describe almost all of the things we do as processes and those definitions are useful and reasonably accurate - they hold true to a common set of characteristics and properties.
So start off with the realization that you can leverage BPM for almost any goal you have. The BPM tools (software, methodologies, guides, books, services, training, experience, etc.) to do all of these things are available to you.
Perhaps that doesn't reduce the confusion, I'm not sure. Perhaps BPM embodies such a broad range of possibilities that it is just naturally confusing. But I personally find it liberating. I have the tools I need to tackle most any challenge, and there seems to always be something new for me to learn just waiting over the next horizon.