Exposure is exactly what it sounds like: putting yourself in situations that cause you anxiety. Your therapist would work with you to slowly build up your confidence and comfort level, starting with situations that cause only a tiny bit of anxiety and slowly working up to situations that are more frightening.
Social anxiety disorder by TeenMentalHealth
Learn a lot about Social Anxiety Disorder. You can read it when you have Social Anxiety Disorder or a friend le someone out of your family has it.