As we have seen, the second Mishna in Massekhet Kiddushin (15b) leaves the realm of marriage and focuses on the status of an eved ivri and specifically on how such slaves are acquired and how they are granted their freedom. While a male Jewish slave is freed from his status as an eved ivri after completing six years of work, or when the yovel arrives or by paying back the value of his remaining years, an amah ivriyah – a Jewish servant-girl – will also be released upon reaching physical maturity.
When discussing physical maturity, the Gemara uses the expression simanim – has the young woman shown “signs”, that is to say, signs of physical maturity. Generally speaking, this refers to the appearance of pubic hairs (in the terminology of the Gemara, shetay sa’arot – at least two hairs). Obviously, every child differs in his or her physical development and there is no precise time when these simanim will appear. The age that they appear depends on many factors, including their family genetic history, issues of climate and nutrition. Nevertheless, there are average times that we anticipate the appearance of simanim, and, as the Gemara points out, if they appear years earlier they will not be seen as a true indicator of physical maturity.
The reason an amah ivriyah leaves her master’s house with the appearance of simanim is because the true purpose of such an arrangement is for the “master” to have his son (or himself) marry the girl. If the betrothal has not taken place by the time she is old enough to be married – in a society where marriages were expected to take place at a young age, the Torah concludes that, “Ve-yatzah hinam, ein kasef – she goes free without any payment being made,” (see Shemot 21:7).