It's when you use the right mouse button to go back from your current screen to the logical previous screen, i.e. attack periscope to conning tower, obs scope to command room, or hydrophone to radio/hyd room. Not all of them were defined in stock SH3 but you can add them in the commands.cfg (with or without SeyKeys).
Well that's what I understand by the 'go back' option. Maybe Mikhayl meant something else
