If you have a coax cable in the wall, it’s very likely you have what you need for home internet, minus the modem and router. Your ISP will set you up with service, and your modem will connect to that coax cable. The router then connects to the modem, and you get wired & wireless internet from there.
I recommend not using modem/router combos that ISPs offer, and getting your own devices. Just make sure that they will work with your ISP service.