A vagina is a muscular canal that connects the cervix (the opening to the uterus) and the vaginal opening of the body. The vagina sits between the urethra and the anus. The vaginal wall consists of tissues which are elastic and can expend at the time of sexual arousal and childbirth. The vagina is where the menstrual blood leaves the body, and it is through vagina that childbirth takes place.
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