Hey, I don't know where you read that from, but you need to plug the ethernet cable from the port on your Pi to the Modem/Router of your local area network service provider, and not to your computer. You're Pi is already a computer in itself, makes no sense connecting it to another computer again for communication over the internet.
Honestly, since you mentioned it's a Raspberry Pi 3, I'd suggest you ditch the hassle of cables and switch to WiFi for your own good.
You can browse through here if you need instructions for setting up your WiFi: https://developer.android.com/things/hardware/raspberrypi