Unlocking an A7 Lite android tablet will give you power to perform any task that would otherwise be not possible. This includes ability to root and flashing different firmwares on the Galaxy A7 Lite tablet.
Before following instructions on how to root Samsung Galaxy Tab A7 Lite android tablet, you must OEM unlock the A7 Lite, and unlock bootloader. For that, follow these steps.
1. Enable developer options by going to Settings > About Tablet > Software information > and tap build number 7 times.
2. Go to Developer options and turn on OEM Unlock.
3. Turn off your Samsung Galaxy Tab A7 Lite tablet, and connect it to the computer while holding Volume Up and Volume Down keys until you see the bootloader screen. Make sure to long-press Volume Up key to enter Device Unlock mode. Now, press Volume Up key to confirm and unlock the bootloader.
That is it. You have successfully unlocked the bootloader of your Samsung A7 Lite android tablet.