What are the signs of puberty recognized in Islamic law and by custom, and what is the ruling on the fasting of a woman who broke her fast during several Ramadans after the appearance of hair [pubic hair] but before menstruation, and is ignorance considered an excuse in this situation?

A woman reaches puberty by one of four signs: completing 15 years of age, the growth of coarse pubic hair, ejaculation, or menstruation. If a woman was unaware of these signs, she is not sinful for not fasting due to ignorance, but she must make up for the fasts she missed after reaching puberty.