I'm new to networking and self-hosting and have no idea where to start.

I've been slowly working my way though a list of skills to learn, both to put on my resume and as personal growth. Networking is the next thing on this list. I am not sure what I am looking for, but I want to start another project. I have built many a personal computer, but the world of networking is a pretty foreign concept to me.

I have experience with building computers and a minor glance at the network-side of things. I've set up a Pi-Hole or two and set a basic CUPS server up on a RPi0w, but beyond that, I have no idea what I'm doing, or even what the possibilities are. I just see posts like this and think that it's a pretty cool hardware project.

Is there any resources you recommend to start learning, maybe what the hardware does? From my outsider's perspective, I see a lot of people's racks have at least a router, switch, and firewall, along with various other machines.

E: thank you all for the suggestions! I'll have to take some time to figure out what to do first