Mesh nodes are APs. If you purchase a 3 node system from whoever, that is three APs. One is the central node connected to you ISP service. Best performance is if you hard wire the other two nodes to the central device. Someone mentioned having WiFi-6E; that includes the newest freq band(6Ghz). For now, 6Ghz is primarily for AP-AP backbone as most client devices do not support 6Ghz. A great way to move 1’s and 0’s.
If you are having coverage issues, step 1 should be to download an app to help you with a wireless survey of your house. Then you can determine if you need new hardware or just move existing equipment.

An “access point” is usually cabled back to your router/switch and provides the WiFi signal to the area around it. You can do it as hallb suggests, which might be easier, or buy an individual access points and place them around the house to give you the coverage you want. I have two to cover my house, older versions of these U6+ units. I used to run three of them and had coverage well beyond my half acre lot. The older unit, the AP-Pro had a second Ethernet port on it that you could use to keep the the wired. I think you can still find those for sale new.

https://store.ui.com/us/en/collections/unifi-wifi-flagship-compact

I got it now, thank y’all.