Create /storage/.restore and place the backup file there and reboot. On restart it will be detected, the dirs that will be overwritten will be deleted (/storage/.kodi, /storage/.config, and /storage/.cache) and then the backup is decompressed to /
You can also use the restore function in the GUI which will copy the file from wherever you have it to /storage/.restore then force a reboot to start the process.
Or use tar commands to extract files and do other things with the backup file. It's just a standard tar archive.