As a general rule, Shape parameters are parameters that cause a device to be placed into the fixture's beam. The most obvious of these is gobo wheels, but also includes animation wheels, prisms, irises and framing shutters. It therefore tends to be moving profiles, spots and beams that have parameters in this attribute.
If your fixture has gobos, you will be able to automatically create shape palettes, to generate a palette for each gobo from all of the fixture's gobo wheels. The first palette will be "No Gobo", allowing you to easily remove any gobos from the beam.
You can also record your own shape palettes, useful for if you want a certain gobo rotating at a certain speed, or useful to save your hard work if you have spent time getting your framing shutters just right.