Humans reproduce using sexual reproduction involving a man and a woman.
The two testes (one is called a testis) are contained in a bag of skin called the scrotum. They have two functions:
The sperm pass through the sperm ducts, and mix with fluids produced by glands (seminal vesicles). The fluids provide the sperm cells with nutrients. This mixture is called semen.
The penis has two functions:
The urethra is the tube inside the penis that can carry urine or semen. A ring of muscle ensures that urine and semen do not get mixed up.