A:Answer The question's a little vague.
You need internet service (AT&T, Spectrum, etc.) coming into your home with a modem, first. This can't be used in lieu of a modem to provide service.
Once that's done, this gets hooked up like so: Modem ---cable--->adapter (plugged into wall.) -----electrical lines in home ----> Other adapter ----cable---- PC. (or switch, or TV. It has two plugs on the bottom.) So yes, you do need a cable - these are not wifi extenders.