You will see a window asking "Are you sure you want to restore the previous version of" followed by the file name and the timestamp on the prior version of the file. The window also warns you that "This will replace the current version of this file on your computer and cannot be undone." Click on the Restore button on that window.
You should then see a window stating "The file has been successfully restored to the previous version." Click on the OK button to close that window. If you click on the General tab at this point, the Modified date will still reflect the timestamp before you restored the file, but if you close the Properties window and reopen it, you should then see the Modified date and time reflect the timestamp of the prior version that was restored to the system.