How secure is "Incoming LAN connections accept exclusively"?

Sorry but I am not that savvy when it comes to networking. But this means that even if people have the IP address of my computers but are not physically connected to my LAN via ethernet, that they won't be able to have access right? And that I can't get hacked that way right?

Especially with a strong password for both TeamViewer Options & to actually access one of my computers via TeamViewer?

Is this good practice for accepting LAN exclusively?