Device Protection, or Factory Reset Protection
Android devices provide built-in security features you can use to protect your device and information including screen locks and data encryption. Data protection, or Factory Reset Protection (FRP), is a security feature on Android devices with Lollipop 5.1 and higher. FRP is automatically activated when you set up a Google Account on your device. Once FRP is activated, it prevents use of a device after the factory data reset, until you log in using a Google username and password previously set up on the device.