A surface mesh refinement allows you to affect the generation of an FE mesh on surfaces.
For an optimal FE mesh of a surface, it may be necessary to refine the FE mesh. This way, it is possible to select an adjusted discretization for surfaces with small dimensions, for example. Conversely, for surfaces that do not play a role in the analysis, you can apply a "refinement" with a larger mesh size than the globally targeted FE mesh length.