'Free motion' means that you aren't quilting with feed dogs, so the motion of the fabric is controlled only by your hands, not by the machine advancing the fabric. Machine quilting can either be free motion, without feed dogs, or straight line with the feed dogs. With free motion quilting, you definitely have a pattern in mind, whether it be a simple meander, or fancy feathers. If you have a long arm machine or a sit down quilting machine, you need rulers in order to do straight lines, because you don't have the feed dogs. But if you will be quilting on a DSM, I don't think you'd have need of the rulers.