Pot likker is the broth or liquid left over after boiling or braising cooking “greens” (leafy green vegetables.)
Though many other cultures discard this, it is used and even prized by many in the American South. Usually it is poured over cornbread or cornbread is dunked in it to sop it up. Some people even drink it straight up.
Pot likker is very nutritious, because it contains many of the nutrients that leeched out from the greens during cooking. Using the pot likker also helps to balance the nutrients that are lacking in the cornbread, because they are tied up in the corn. If you just ate cornbread by itself a lot as a staple, you could develop pellagra.