Very simply Lean has several facets. One one hand Lean is a way of looking at anything you do and trying to come up with ways to make it better, faster, cheaper, or more error-proof.
We think of these as "the tools of Lean". We set up processes and procedures so they can work for anybody with minimal training.
Another facet is the people-centric view of including people in the process. This is the "human side of Lean" and both facets are important.
We include people who work the process in the changes to get their input and buy-in so that the countermeasures applied actually work for the people who need it. Have you ever had someone observe what you do and then attempt to "help" you by making changes without ever asking you what you need or taking time to understand why things are done a certain way? It's usually not that helpful unless you can be a part of the problem-solving process from the beginning.
Lean commonly starts with evaluating the current state of the operation or the current condition. This can be through a tool, like a 5S audit, that shows the 5S condiiton of the operation. It could also include production metrics, like cycle times, lead times, reject rates, or cost or margins. Some of these would be identified using a process or Value Stream map.
Once we identify areas of opportunity, we would then examine the operation step-by-step and identify any of the 8 Wastes that are involved. What is Transactional Office Lean?
Then, prioritize the opportunities based on business need, ie. add capacity, reduce cost, improve lead times.
Root cause analysis will help to target the areas to be improved.
Once specific processes or sections of processes have been identified as needing improvement then standard Lean tools, like 5S, Standard Work, or Setup Reduction can be applied as needed to make the activity better.