DP in WhatsApp stands for display picture. People sometimes and often times want to display their picture so that others can see who they are. If the people have known you for a while, then it is probably okay to display your picture. However, there may be times when you don’t want to display your picture due to concerns over your privacy. Also, you are displaying your image to people you don’t know.
So, you may want to hide your WhatsApp display picture from certain people. You can always delete the person’s contact information from your WhatsApp. Then they won’t have access to any of your information including your display picture. You can just hide your display picture by clicking on settings, account, privacy and then your photo.