Desangran literally means "bleed out" or "drain of blood." It's a very strong and evocative verb that you don't often hear in everyday conversation or even in many songs.
In this song, Alejandro Fernández uses it metaphorically to express the intense pain and suffering of his unrequited love. He sings, "Cómo desangran en tus ojos mis anhelos" (How my longings bleed out in your eyes), painting a vivid picture of his desires being painfully revealed and perhaps dying in the gaze of the person he loves. This dramatic imagery makes the word particularly memorable and impactful.
Have you ever been so in love that you just want to shout it from the rooftops, but you're afraid the person doesn't even know how you feel? That's exactly what Alejandro Fernández is singing about in "Si Tú Supieras" [If Only You Knew]. He's pouring his heart out, wishing the object of his affection knew the depth of his feelings. He describes how her memory "me acaricia como el viento" [caresses me like the wind] and how his heart is speechless trying to express such a grand emotion.
He's practically begging for her love, saying "Ven, entrégame tu amor" [Come, give me your love] to calm the pain of not having her. He wants to erase his laments with her caresses and plant a thousand new roses in her being. It's a powerful plea, full of passion and longing, as he declares that the whole world isn't enough to love her. He's even dying inside from the desire to give her all the passion he carries. Talk about intense!