It is the age of the changes not only physical, but also emotional. It is about puberty that usually begins between eight and 13 years of age in girls, and between 10 and 15 years of age in boys.
In some minors, puberty begins before or after those ages, which is why some people still seem younger, while others become more mature.
During puberty, girls and boys may feel confused or feel strong emotions that they have never felt before. They are likely to notice that they are too sensitive or angry easily.