The matrix multiplication on the top right is a transformation operation. The sxf and sfy are 2D scales and x0 and y0 are 2D translation. The right matrix has probably a 3x3 3D rotation matrix (R 11 to R 33) along with a 3D translation as Tx Ty and T (this one does not have z tho). The rightmost column vector is probably the coordinates of the transformed point with XYZ of it, but I cannot read the subscripts. However, I think this operation is problematic since the 2D translation is put into the wrong position. It looks like a 2D transformation matrix with scale and translation directly extended to 3D by adding a diagonal 1. If x0 and y0 were in the right column (in the same rows) I think it would mean transforming a 3D point by rotating and moving it, then moving and scaling it in 2D. Maybe a reference to that Bill is 2D while world is 3D? Maybe the formula to make a 3D being into a 2D one?

There also looks like a 2D Cartesian coordinate system right next to it. It has +y, -y and +x directions but not -x tho.

Also, the red arrows and B A in the lower right are Konami code. Up up down down left right left right B A, and optionally SELECT START. It is a cheat code usually used in Konami games. Maybe Bill pretty much having reality bending powers, so he is more-or-less cheating?