phrase details about sexual activity and the way that babies are born: 性知识;生育常识 He decided to have a talk with his son about the facts of life. My school was woefully inadequate when it came to teaching us the facts of life. She was 17 before anyone told her the facts of life. He begged his parents to tell him the facts of life but they refused. I take it you are familiar with the facts of life? See also
fact
facts of life | American Dictionary
facts of life
idiom the details about sex and sexual reproduction