Radharani is the internal potency of Sri Krsna, and She eternally intensifies the pleasure of Sri Krsna. Impersonalists cannot understand this without the help of a maha-bhagavata devotee. The very name “Radha” suggests that Srimati Radharani is eternally the topmost mistress of the comforts of Sri Krsna. As such, She is the medium transmitting the living entities’ service to Sri Krsna. Devotees in Vrndavana therefore seek the mercy of Srimati Radharani in order to be recognized as loving servitors of Sri Krsna.

From Srila Prabhupada’s purport to CC Adi 4.56