"Safety backups" are a safe restore point. The safety restore point is created for the account before JetBackup starts the restore process (only for full Account). It can be useful if for some reason the restore was not successful or as expected. So you can always go back to the original starting point. Safety backups are removed automatically on the daily cron job. To restore an account from a safety backup you should follow the same procedure as restoring from a "regular" backup. The only change is that you will see a "safety" location when you choose your restore point.
You can set the safety backups to be restored automatically. Go to "Restore Settings" and set the 'Auto rollback failed restore accounts' option to your preferred automated method. If you didn't set this option you can restore it from the queue or via shell command that you can find in the failed backup log.
To restore through the queue hit the 'Rollback - Latest Safety' button.
To restore through the shell go to 'Logs', then enter your log file.
At the end of the file, you will find the shell command to restore your account from your safety backup.