For geometry import from CAD a preview dialog is shown first:
This dialog shows the number of parts available in the file and allows to delete parts and merge the remaining parts. The part can be remeshed with different settings to evaluate the mesh quality.
Only the currently selected part is meshed and imported. To combine parts the "Merge" function has to be used and a reasonable merge tolerance has to be set. After meshing the number of surface nodes is shown in the window to get an idea about mesh complexity.