Without saying much about Brahmacharya, Maharshi Pathanjali directly mentions the benefits of brahmacharya.
The practice of celibacy is one of the most important yama for the people holding the office of the priest and other religious activities and for those who have renounced worldly life.
Brahmacharya is the mastery of the five indriyas, the senses.
We have two important characters in our Sanatana Dharma. They are Indra and Apsara. Indra is the king of gods and Apsara is the most beautiful damsel in the court of king Indra.
The person is a scholar and has an impeccable character. But he is a poor person. He has a large family to support, but he has no resources. He cannot beg due to various reasons.
"One who marries and begets children in the pursuit of dharma alone and without being subjected to the passions, seeks the company of his wife for that purpose on approved days only, is known as a brahmachari." ----- Maharshi Vashista.
One who practises brahmacharya is called a brahmacharin.