This function "swirls" an image, this means, it looks like it gets whirled by a water swirl. Angle controls, how much to swirl.
The normal operation of swirl is to fix the center of the image and to move the pixels around this center. If Inverse Mode is turned on, the edges of the image will be fix and the movement will be larger towards the center.
If the Steps value is larger than 1, PhotoLine will not modify the active layer but creates new layers. The result may be viewed as animation.