This boy is acting as young Krishna in a theater play (Ras Lila) where stories of Krishna's life are being shown to a huge audience
Ras lila is a popular form of folk theatre in the regions of Mathura, Vrindavan in Uttar Pradesh, especially during the festivals of Krishna Janmashtami and Holi, and amongst various followers of Gaudiya Vaishnavism in the region. It revolves around the story of the love between Krishna and the cowherd girls as well as th childhood of Lord Krishna. The Traditional Rasa Lila performances in Vrindavan are famous throughout the Vaisnava world as an experience of the spiritual world. Rasa Lila performance was started in the early 15th Century CE at Vamshivata in Vrindavan, Mathura.