What does it mean if the penis is changing color. The normal color is brown but near the shaft it's getting all white. ?

Skin disease. This can represent vitiligo a loss of color, or other skin conditions such as lichen sclerosis, or less commonly hypo pigmentation following psoriasis, lichen planus, dermatitis. Repigmentation is possible when treat, ENT is started early with creams and excimer laser.
Usually nothing. Loss of pigment in the skin can reflect an inflammation in the skin or an autoimmune condition called vitiligo which is harmless but cosmetically of concern.