Disable Tablet Button Panel: When this box is checked, the Tablet PC buttons are disabled. You must reboot the system before this action will take effect.

Depending on your system "Fn" button may not be present. If it is present , "Disable Fn + Fn Button Functionality" checkbox is displayed.
Disable Fn + Fn Button Functionality: When this box is checked, you will not be able to invoke the Fujitsu menu using the Fn + Fn shortcut.