“Son of Mitzvah"
From the age of thirteen, Jewish boys are considered adult men who are obligated in all mitzvos, or commandments. For this reason, on his thirteenth birthday, the Jewish boy is called a “Bar Mitzvah," literally “son of mitzvah."
We make a distinction between an “ish," or man, and a “non-ish" regarding the keeping of commandments. In several places our sages have interpreted “ish" as a time when the boy's body starts going through physical changes; prior to these changes, he is considered a minor and is not obligated in any commandment. In spite of this, however, our sages have decreed that once a boy reaches the age of thirteen and a day, meaning once he starts his fourteenth year, he is still obligated to keep all commandments.
There are different opinions regarding the source of the age thirteen. In the Torah, it seems to be hinting at the fact that thirteen is considered an “ish," or man: “And it came to pass on the third day, when they were in pain, that two of the sons of Jacob, Simeon and Levi, Dinah’s brethren, took each man his sword, and came upon the city unawares, and slew all the males." (Genesis 34:25). In this description, the Torah says “ish charbo," each man his sword, intimating that they were men at the time. Juxtaposed with the fact that Levi had just turned thirteen, it can be derived that this age demarcates manhood.
However, some say that the source of age of Bar Mitzvah was passed down as oral tradition from the time Moses received it.
When reaching Bar miztvah age, Jewish boys are entitled to a number of rights, including:
Receiving an aliyah.
If he is a Kohen, the Bar mitzvah boy is allowed to bless the praying congregation with the Kohanim’s blessing.
Leading grace after meal, also known as zimun, or being one of three men who are necessary to perform the zimun.
Leading prayer services.
The bar mitzvah boy receives an aliyah, a reading from the week’s Torah portion. This is one of the first public "indications" that he’s he has left boyhood and entered manhood. Once the now-man finishes reading the Torah, his father recites the blessing “baruch shepetarani m’onsho shel ze," thanking G-d for discharging him from being punished his son’s negative actions. Until that moment, the father was obligated to teach his son about the different commandments. Now, however, the boy is responsible for his own conduct.
However, with great power comes great responsibility. Some of the responsibilities that Bar mitzvah boys are obligated in are the donning of the tefillin, fasting on fast days, and the concept of arvut, responsibility for others.For instance, if we know someone who is sinning, it is our responsibility to try to rebuke them and get them to repent and stop the wrong action.