“Maintenance Mode is a way of creating a separate user account when you hand in your device to be repaired so they can operate core functions without being able to access to any of your private information. All the user needs to do is select Maintenance Mode in the “Battery and device care” menu within “Settings” and reboot their smartphone. As soon as it’s rebooted, all their personal information including their photos, documents and messages will be restricted”

Source : Samsung Releases Maintenance Mode, A New Feature To Hide Your Personal Information From Prying Eyes – Samsung Global Newsroom