As an IT professional, when you say "Network port" I think it's the physical port on the computer you plug the network cable in. E.g., the ethernet port.

If you're asking "What is a port in networking terms?" that gets asked pretty often, but the bottom line is that you have one network cable and one network address, but you can run multiple services on that connection, and ports are used to differentiate them.

So the software on the connecting side will go "Hey, I'm trying to talk to port 443" and the networking software on the target will go "hey someone's trying to reach port 443, anyone listening to that?" and a piece of software (in this case, the web server) will say "Oh yeah that's me."