Backup takes the entire database file from the internal memory to the application installation folder. Default backup folder is ~/ThisJournal/Backup and ~/ThisJournal/BackupZip for zip files.
Starting with 4.2.2, Backup was updated to create a .zip with option to include Media folder which contains photos. This is done manually, the auto backup only takes the internal database file.
An option was also added to upload the zip file to Google Drive, you need to have a Gmail account for this.
Restore restores the whole database file, any existing data is removed. Restore requires a device reboot.