When the emperor was young, he was precocious. When he was a teenager, there would be female officials around him to impart that knowledge. That's a sex teacher. When the emperor grows up, ordinary female officials will be given concubines.

Concubine In ancient times, women were strictly disciplined. Only when they get married, their elders, such as aunts, tell them what to do, and they get an erotic book (the kind with pictures). (Women are precocious. Many women are generally confused in their youth and will peek at erotic pictures. )