The term cube steak is used to refer to a cut of meat that has been run through a mechanical tenderizer called a meat cuber or swissing machine. The resulting steak is called a cube steak (or swiss steak) because of the cube-shaped indentations made by the tenderizer.
Cube steak can also be made by pounding the steak with a tenderizing mallet to produce the cube-shaped indentations.
Traditionally, cube steak is taken from the beef round primal cut, which is well exercised and quite tough, or from the shoulder center, which comes from the beef chuck.
But it can be made using any tough cut of beef.
Cube steak can be braised, sautéed or pan-fried. It can even be baked in a casserole. Examples of cube steak recipes include pork cutlets and Swiss steak.
It should go without saying, but I'll say it anyway, that the whole point of cube steak is to tenderize a tough piece of meat. Therefore you would not want to make cube steak from a higher quality (and thus more expensive) steak such as a tenderloin or ribeye steak.