Condena means "doom" or "curse," and can also refer to a "sentence" as in a trial. It’s a beautifully dramatic word for a pop song, hinting at a deep, inescapable sorrow.
In "Caraluna," the singer says, "esa luna es mi condena" (that moon is my curse). The moon constantly reminds him of his lost love's face, turning what should be a beautiful sight into a painful, nightly torment. This single word perfectly captures the song's theme of being haunted by a memory.
Ever been haunted by a memory? In "Caraluna," the singer is stuck on someone who's gone, and everything reminds him of them. The title itself, which means "Moonface," comes from the main idea: "Mientras siga viendo tu cara en la cara de la luna" (As long as I keep seeing your face in the face of the moon). He's at the beach, a place they once shared, but now their footprints have been washed away by the sea. The moon, however, is still there, and he calls it his "condena" (curse or sentence).
What makes this song so clever is that he knows he's stuck. He admits he's using this person for creative fuel, saying "te siga usando así / Robándote en mi inspiración" (I'll keep using you like this / Stealing you for my inspiration). He hears their voice in the waves and has to change the radio station because every song is about them. He feels like he's either searching for them or escaping from himself, and he's not even sure which it is. It's a perfect song for when you can't shake a memory, and you've started to turn it into art.