Brahmacharya Means the one self-existent Spirit, the Absolute Reality
Bramcharya is broad sense it means control of the senses or indriyas. More specifically it refers to celibacy or chastity.
Brachmacharya is considered one of the cornerstones of a serious yoga practice.
The conservation of energy that comes from practicing celibacy is converted into Ojas and Tejas (spiritual energy). Eventually yogic powers can also manifest by the perfect practice of brahmacharya.
There are many famous yogis and spiritual leaders who were established in this yama. Some of them are Sankara, Jesus, Gandhi, Hanuman, Lakshmana, and Bhishma from the Mahabharata.