Gembutsu is a Japanese word meaning ‘real thing’. It is one of the components of the ‘Three Reals‘ meaning go to the real place (gemba) to see the real thing (gembutsu) and collect the real facts (genjitsu).
This term simply means that there is no substitute for seeing something with one’s own eyes. Far too often, people hear about a process or problem, and take what they hear as fact. Watching an actual item being made or form being processed gives an increased level of insight that helps with problem solving as well as making improvements.