Fastboot allows to flash a custom recovery image or in some cases only boot with custom recovery. Fastboot does not require USB debugging to be enabled on the device. Not all Android devices have fastboot enabled. Each manufacturer has a different way to enter Fastboot.
You will get root access to the device.
When flashing the custom recovery to the device it writes to the system permanently. It needs to have an unlocked bootloader, unlocking the bootloader may cause to delete of all data of the device
On the Main page click on “Security Bypassing”.
Choose “Generic profile” and click “Next”.
Choose “Connect Fastboot” and click “Next”.
Select from the list which type of device you have, then read on-screen instructions of how to put the device to Odin mode and click “Next”.
Follow on-screen instructions.