Al-Jawab Billahi At-Taufeeq (the answer with Allah's guidance)
To be Baligh, (to be physically matured) is one of the conditions that make Salah, Sawm and Hajj compulsory. In the case of the male, it is from when the signs of puberty appear, e.g. wet dream, growing of beard, etc. If there are no signs, then from the age of 15 lunar years.
In the case of a female, it begins at menses or if there is no menses then at 15 lunar years.