Red dots like this pop up all the time. Why?
You can get acne anywhere on your body, including your penis. What you are seeing is a clogged oil gland. The white center is the oil building up underneath the skin because the exit hole got blocked. The red around the area is because an infection has set in. Most likely due to bacteria also being trapped underneath the skin.
For what to do about it, see: What are the best natural ways to get rid of acne?