Process mapping records how a piece of work flows from start to finish: what triggers it, who handles each step, what information is needed and where handovers happen. The important word is really. A map of how things are supposed to work is far less useful than one of how they do.
Once the work is visible, the delays, duplicate entry and workarounds stand out. The map becomes the basis for writing procedures, deciding what to automate and designing software that matches the business. It is the first step in how we work, and the one that makes everything after it cheaper and more accurate.