Do I need a switch, a router, or both?

Hello. I’m planning a SOHO network setup for my dad. It needs to have seven wired ethernet ports (wireless is not an option for a variety of reasons), and support QoS (due to VOIP). It also needs to share his broadband (cable) internet access.

My question is, do I need a network switch for this, or a broadband router? I’ve always used routers in the past, but very few offer seven ports. I’ve never used a switch before, but they seem to be readily available with the ports I require. Can such a switch simply be plugged into his existing router to add some more ports?

Finally, I would be most grateful for any links to hardware that would fit my needs, if anyone has an reccomendations. Thank you kindly for your attention.

-John Price