Bar is Aramaic for “son,” and Mitzvah is Hebrew for “commandment.” Therefore, Bar Mitzvah means “son of the commandment.” In the Talmud (the Hebrew law), this term is applied to every adult male and means that he is a man of duty.
The celebration of the Bar Mitzvah arose a few centuries ago. It takes place when a young boy turns 13. This is the time, by Hebrew custom, when a boy is considered an adult because he is responsible for his own religion. At the celebration, each boy reads a portion from the Torah and speaks about a religious topic.
This is basically a coming-out party with religious implications. Sometimes, now, girls have a similar celebration of their own called a Bat Mitzvah.
“That through them I may prove Israel, whether they will keep the way of the LORD to walk therein, as their fathers did keep it, or not” (Jdg. 2:22).
“And thou shalt remember all the way which the LORD thy God led thee these forty years in the wilderness, to humble thee, and to prove thee, to know what was in thine heart, whether thou wouldest keep his commandments, or no” (Deut. 8:2).