I have this white circle-shaped thing in my scrotum. Can you tell me what is this? Is this a disease or something?
I note that the skin in the lighter area looks normal, just lighter in color. Assuming that you have no other symptoms, such as scaling or itching, my best guess is that you have vitiligo. This is a condition where some of your skin cells stop producing skin pigments. It is not harmful or contagious.
You can double check with your doctor, but it doesn't appear to be anything to worry about.