Level 2 explained

First of all FF, BB, FB and BF stand for respectively:
Forwards-Forwards (FF) meaning both arms move forwards,
BAckward-Backward (BB) meaning both arms move backwards,
Forward-Backwards (FB) means that the left arm travels forwards while the right arm goes backwards while
Backwards Forwards (BF) means that the left arm travels backwards while the right arm goes forwards. In all cases the movement of the left arm is signified by the left letter and the movement of the right arm by the right letter.

Throughout this sight it looks like I've labelled the pictures consistantly wrong because while it might say right arm forwards and left arm back (BF) the picture shows the opposite. That is so that if you mirror the picture the instructions will correspond to what you are doing. This applies both to the description of the movement and the arm positions.

What does Vertical-Horizontal and Horizontal-Vertical mean?
Simply the plane that each hand is in. In the vertical plane the palm is vertical while in the horizontal plane the palm is horizontal so...
Vertical-Horizontal means that the left arm is in the Vertical plane and the right arm is in the Horizontal plane (but in the pictures I'll be doing the opposite.

One of the "ideas" of the dance of shiva is to exercise all possibilities. One of the ways we do this is by going through all possible movement combinations as well as by travelling through all possible positions.

In Level 1 we covered all positions where both arms were in the horizontal plane and where both arms were in the vertical plane. In Level 2 we cover all positions where one arm is in one plane while the other arm is in the other plane.

In both levels we cover all combinations of forward and backward movements, so we do both arms forwards, both arms backwards, the left arm forward while the right arm goes back and the opposite, left arm back while the right arm goes forwards.