Lagos open this one with a jealous, sarcastic sigh: "Que bien debe ser" (How nice it must be). The singer is talking to an ex who seems to have walked away untouched, someone who can "tener a todo el mundo a tus pies" (have the whole world at your feet) and "recibir sin corresponder" (receive without giving back). Meanwhile he still wakes up with "el fantasma de tu pelo atado" (the ghost of your tied-up hair) on his pillow, which is a very specific and very sad little image.
The chorus, "Yo quisiera ser como tú" (I wish I could be like you), is bitter rather than admiring. He wants to "herir como si nada importa" (hurt as if nothing matters) and "amar con la memoria corta" (love with a short memory). The second verse gets darker and a bit funny: he would like someone to "transplante tu corazón con el mío" (transplant your heart with mine) just so that, for once, "tengas pesadillas tú conmigo" (you have nightmares about me). By the end he gives up the act: "Yo lo siento pero no puedo ser como tú" (I'm sorry, but I can't be like you), because "a mí sí me duele y sí me importa" (it does hurt me and it does matter to me).
Learner tip: "Pa'" is the spoken short form of para, and "lo bien que se te da" means "how good you are at it", a handy everyday phrase.