You are working your slipper

You are working your slipper in the geometric stitch pattern.

Many directions will have a section at the beginning where any special stitch pattern is described, as well as special abbreviations, before going into the directions for the item itself. That is the case with this pattern. It tells you first how the geometric stitch pattern will be worked so that when it comes time for the slipper directions, it can focus on how to make the slipper itself.

If it is the slipper, rather than the design on the slipper that appears to you, you could make it in just one color.