x, y, z: Are describing the coordinates of the vector denoting the axis of rotation which can be a positive or negative number.
Degrees: Is an representing the angle of the rotation. A positive angle denotes a clockwise rotation, a negative angle a counter-clockwise one.
Perspective: Is a CSS property that determines the distance between the z=0 plane and the user in order to give a 3D-positioned element some perspective.
Rotate X: is a CSS function that defines a transformation that rotates an element around the x-axis (horizontal) without deforming it.