Penis is a part of the male reproductive organ through which urine and semen (mixture of sperm and fluids) are discharged from the body. A penis consists of tissues which fills with blood at the time of sexual arousal which makes the penis erect. In case of an uncircumcised penis the head of a penis is covered with a foreskin which at birth is attached to the penis but with time separates and can be retracted. A circumcised penis is when the foreskin is surgically removed.
Sources:
https://my.clevelandclinic.org/health/treatments/16194-circumcision
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/reproductive-system
https://www.merriam-webster.com/dictionary/penis
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/foreskin-care