Prem refers to elevated love. Love in Hinduism is a sacred emotion encompassing the concepts of selfless service, compassion and, not expecting anything in return.
"The central value in human life, which we may term "true love," means that which seeks the best for others and the betterment of human life in all its dimensions. True love means living for others, giving without thought of a return. Its source is transcendental, beyond the self; the person who practices true love taps into an inexhaustible reservoir of life. The various philosophies and religions of the world speak of this value with a variety of emphases, aspects, and concepts, such as: compassion, grace, justice, charity, liberation, righteousness, and agape love.... This value, true love, is the aspiration and hope of all human beings and the manifestation of the best in human nature."