Girls reach their religious majority at twelve. This is known as Bat Mitzvah. At this stage a girl becomes responsible for observance of all the appropriate Mitzvot; and for example, she is now obliged to fast on Yom Kippur.
In recent years it has become popular for girls to celebrate their Bat Mitzvah with a small ceremony in Shul at the end of the Shabbat service, when she can, if she wishes, give a Dvar Torah (short speech with religious content) to the congregation.
Nowadays some families make celebrations to mark their daughters’ Bat Mitzvah, on a similar level to a son’s Bar Mitzvah.