What is the ruling regarding the missed prayers and fasting of a girl who was unaware that the appearance of pubic hair is among the signs of puberty?

The growth of coarse hair around the pubic area (pubic hair) is one of the signs of puberty. This is the view of Malik and Shafi'i, and it is supported by authentic hadiths.

Accordingly, if you abandoned any obligatory prayer or fast after reaching puberty, it is a debt upon you that must be made up. If you are unable to determine the exact amount, then make an estimate and make up what you are certain of, or predominantly believe, will clear your liability. This is the ruling given in fatwas, it is the more cautious approach, and it is better for absolving oneself of responsibility. There is a difference of opinion regarding the obligation to make up prayers missed due to ignorance of their obligation.