This means that the sharpening of a certain knife was done on a water sharpening stone with a grit of 3000 units (#3000).
Any knife sharpening is carried out in several stages, the number of which primarily depends on the degree of dullness.
Coarse, using sharpening stones from #400 to #1000 – the correct angle (cutting edge geometry) is formed with coarse abrasives.
Medium, using sharpening stones from #1000 to #3000 – finer abrasives are used to grind to the desired smoothness.
Finishing, if necessary, using sharpening stones from #3000 to #8000 – edges are polished to a mirror shine (finishing).
To maintain the sharpness of kitchen knives at home, two stages with sharpening stones from #1000 to #3000 will be sufficient.