A scrotum is a part of the anatomy for people with penis. It is a skin sac like structure divided into two compartments to contains the testicles and hang outside of the body under the penis. The scrotum hangs outside the body because it needs to maintain a temperature lower that the body.
Sources:
https://www.healthline.com/human-body-maps/scrotum
https://www.hopkinsmedicine.org/health/wellness-and-prevention/overview-of-the-male-anatomy
https://www.britannica.com/science/scrotum
https://www.ncbi.nlm.nih.gov/books/NBK549893/