You connect one end of ghe cables into the built-in nic cards. what will you plug the other emd into

I’d say a network drop is the answer in this case.

A drop is a connection point in a network. There are those typical wall mounted plate outlets with an Ethernet jack that look like sockets that a computer or any other device in a network can plug into. A drop cable is used to connect a computer’s NIC card to these wall plates.