In the movie little Anjali reads the 8th letter from her mother on her 8th birthday?
Assuming that little Anjali’s grandma kept her promise to Tina and gave a letter to little Anjali on each one of her birthdays, then we can conclude that little Anjali received her first letter at the age of one, her second letter at the age of two, etc…So little Anjali was able to read and understand Hindi by the age of one.