When the History Get command is clicked, the Get Latest Version dialog box will open on the selected version of a file or folder. For example, if the current selection is a file checkin, it gets the version associated with that check in. If the current selection is a folder, it will retrieve the files (and their versions) that existed at the time of the selected folder version.
If you choose to get previous versions into the current working folder, it will overwrite what is there. If a file to be overwritten has been modified by you since the last time it was retrieved from the repository, it will be backed up in the _sgbak folder within the working folder.
For more information, please see History Explorer.