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 play a minor role in the analysis, you can define a "refinement" with a larger mesh size than the globally targeted FE mesh length.