The elements of a 'rite of passage' can vary in their extremes from one culture to another - and some of them can be very scary indeed!
In general terms, a 'rite of passage' is some sort of ceremonial marking of a human's passing from one important stage of life to another. A common example would be the passage from boyhood into manhood. Following some sort of ritual, the person has a new, higher status and is usually given more respect and sometimes responsibility.
This rite can vary according to the society a person lives in. In some tribes there may be initiation ceremonies or even tests or dares to prove bravery. Some involve withstanding pain, hunting or maybe just a long period of isolation from the tribe.
Bar Mitzvah and Bat Mitzvah, Baptism, Marriage,Confirmation and First Holy Communion would be examples from various cultures of marking new beginnings and transitions.