There is only one file type that uses the .LBF extension:
LG Backup File
An LBF file is a LG backup file created by the LG Backup application preloaded on LG phones running Android. It contains a backup of data on your smartphone including applications, calendar entries, contacts, settings, and messages.
The Backup application can be used to perform manual backups or schedule automatic backups of data. It can also be used to restore data from the backups. On the home screen, tapthen select to create a backup, to schedule an automatic backup, or to restore a backup.
Updated: January 3, 2017