O believers! Let your servants and those children who have not yet attained puberty ask your permission before coming in to see you on three occasions: before Fajr Salah (dawn prayer), at noon when you put off your clothes, and after the Isha Salah (night prayer). These are your three times of privacy. At other times, there is no blame on you if you, or they, go around visiting one another. Thus Allah makes His revelations (verses) clear to you, for Allah is All-Knowing, All-Wise.
Meaning:-
Puberty: the period or age at which a person is first capable of sexual reproduction of offspring.