The youngster, with a basic Vedic learning, is taught during the ceremony, the secret of life through Brahmopadesam(Preaching/Advising on the nature of Brahma - The Ultimate Reality) or the Gayatri mantra.
He then becomes qualified for a life as a student or Brahmacharya, as prescribed in the Manusmriti
In modern India, this practice has all but vanished from the Hindu society and is noticeable only among members of the Brahmin community.