Android Factory Reset Protection (FRP) is a new feature to protect your device which has been added to several Samsung devices that are running Android OS 5.1 or higher.
This feature allows you to set up your device to prevent other people from using it if its been reset to factory settings without your permission. For example, if your device is lost, stolen, flashed, or wiped, only someone with your Google account or screen lock information can perform a factory data reset and use the device.
When a device is factory reset, the device will not be able to be setup without the user entering the Google Account associated with the device (for hard reset) or screen lock information (for reset in Settings menu).

Important! You must set up a Google account in order to utilize the FRP feature. It is highly recommended that you set a secure screen lock on your device.