Answer
The honorific Srila Prabhupada was extended to A. C. Bhaktivedanta Swami Prabhupada after his death. This was done to honor his life and work as a spiritual leader and teacher. Prabhupada was a key figure in the revival of the Gaudiya Vaishnava tradition of Hinduism, and his teachings have been influential in spreading awareness of this tradition around the world.