Pretty much anything you’d use a second port for on any machine. You could use the machine as a router, or just a firewall to partition part of the network you want almost, but not quite, completely isolated, you could run the system management traffic on one port and general traffic over the other or trunk them together for greater resilience or more bandwidth (though I’m not sure a lower spec machine could really benefit from that). There’s bound to be other uses, but those are what I came up with off yhe top of my head.

Using it as a router