Turns and Change of Direction refers to skills that either change the direction you are facing or the direction of the jump rope from forward to backwards, or vice versa.
Power means multiple unders and will likely take longer to learn. The first skill listed is a double under and learning the first double under takes patience and practice. After that we progress to variations on the double under, and triple unders.
Manipulation refers to the variety of ways you can manipulate your rope. This includes rope poses, swings, and wraps. Manipulation skills are very popular and often relatively success-oriented.
Strength & Inversion
Strength & Inversion skills refer to moves that require a change in body position such as squatting, plank, cartwheels or moves that require large muscle groups or physical strength to achieve.
Arm Action skills are very similar to manipulation, but it made sense to separate them out for organizational purposes. Most arm action skills are arm crossing skills, but there are a few exceptions.
There's 23 different foot skills on the footwork poster, but really, anything you can do with your feet would be considered footwork. Try mixing and mashing moves to create unique foot patterns. Try all footwork moves without a rope first.