Plenilunada is a beautiful and somewhat rare adjective derived from plenilunio (full moon). It describes something that is bathed in the light of a full moon.
In the song, the singer yearns for a night that is plenilunada, emphasizing the deep longing for the return of his loved one and the light she brought into his life. It evokes a strong sense of romantic melancholy and vivid imagery.
Vicente Fernández's "Luz De Luna" is a beautiful, melancholic song about a love lost and the profound emptiness it leaves behind. The singer desperately longs for the "luz de luna" [moonlight] to illuminate his sad nights, a light that vanished the moment his beloved left. He needs this moonlight to remember the "divina la ilusión que me trajiste" [divine illusion you brought me] and to feel her as "mía tú, como ninguna" [mine, like no other].
He describes feeling her absence like "amarras como garfios, como garras" [moorings like hooks, like claws] that are drowning him in a sea of partying and pain. Even in the quiet night, he hears her "cadenas arrastrar" [chains dragging], a powerful image of how her memory still binds him. If she never returns, he hopes her memory will at least "ponga luz, sobre mi bruma" [put light on my fog], because without her, his world has been without moonlight.