You can use this event to rotate a group. The new rotation angle must be specified in degrees (0 to 360). The group objects will be rotated around their anchor point which is usually set at 0.5/0.5 which means rotation should be done around the object's center point.
You can also use variable names instead of numeric constants with this action event. It is even possible to enter complete expressions like "x+1" or function calls for maximum flexibility here.