We mentioned back in Mitzvah #176 that there are four people who are called “mechusar kaparah” (“lacking atonement”). These people go through their respective purification process and immerse in a mikvah, but they may not eat from sanctified foods until after they have brought their sacrifices. The four are the woman who gave birth (Mitzvah #168), the metzora (Mitzvah #176), the zav (Mitzvah #179) and the zavah (this mitzvah). You will notice that “metzora” includes both men and women with tzara’as, but zav and zavah are listed separately. This is because, similarities aside, the zav and the zavah are affected by completely separate forms of ritual impurity. Yes, each had a genital discharge, but the nature of each of these is definitely gender-specific. (For example, a man would only become a zav for a white discharge but a woman could only be rendered a zavah for a red discharge – see the Rambam’s Sefer HaMitzvos, positive #75.)
Like the zav, the zavah’s sacrifice consisted of two birds (pigeons or doves), one of which is offered as a chatas (sin offering) and one of which is offered as an olah (burnt offering). As I mentioned in the previous mitzvah, I’m not sure why a zavah brings a chatas, but she would probably be well-advised to use her week of impurity and the experience of bringing the offering for personal introspection, as is the case with the metzora and the zav. While we have not been told that the zavah is responsible for her own condition, ultimately everything that happens to us is a message that we should try our best to interpret. (The Rambam does say that the chatas offerings of a zav and a zavah are not for any sins, but we previously attributed the zav’s condition to his own deeds, so it’s not unreasonable to look for a cause here as well.)
This mitzvah only applies at a time when the Temple service is in effect. It is the discussed in the Talmudic tractate of Kerisus on page 2b. It is codified in the Mishneh Torah in the first chapter of Hilchos Mechusarei Kaparah and is #75 of the 248 positive mitzvos in the Rambam’s Sefer HaMitzvos.