This is primarily a display of any Exchangeable image file (Exif) tags added by the camera or other photo editors. Only jpg images have this information which may include tags from the camera such as GPS location, shutter speed, camera name, focal length, and many other tags. Pictures converted from other file formats won't show much but Photo Sieve adds enough to store any comments or tags you add.
Click on an Exif tag to highlight and select it. When the "Tags" tab in the Overview window is selected, the "Tags" menu is enabled. Menu "Tags/Add Exif Tag" adds the selected Exif tag as a new column in the Overview window "Tags" tab.