Hi jaymac, the ethernet cable takes the place of a WiFi connection, it is an option giving a hard wired Internet connection. My WiFi booster had an ethernet socket and so I used it.
It is a smart TV so I can access the Internet and I get my TV from Freeserve. It is an excellent TV, 43 inch and about £350 with a 6 year warranty.
I can use Alexa and just ask for the TV programme or a You tube video as I feel like it. Or I have the 'magic' remote control for electing channels as normal.
Roy