Every timestamped click, status change and approval in a system such as an ERP or a ticketing tool leaves a trace. Process mining software reconstructs the actual sequence of steps from those traces, which often looks different from the process diagram a team drew up: extra approval loops, steps done out of order, or a handful of people who touch nearly every case.
The value is finding the real bottleneck before automating anything, since automating a broken sequence just makes the broken sequence faster. The limit is that process mining only sees what the connected systems recorded, so work done outside those systems, such as a phone call or a side conversation, does not show up in the map.