Macaco and Monsieur Periné take the idea of sign language and turn it into a love song about two people who barely need to talk. The hook says it plainly: "lenguas de signos, dos cuerpos callados, dos cuerpos que hablan" [sign languages, two silent bodies, two bodies that talk]. They even "inventamos nuestro propio idioma" [we invented our own language], one made of glances, lips and fingertips.
The fun is in how the song borrows grammar words for romance. Their language has "sin puntos ni comas, ni acentos desiguales" [no full stops or commas, no uneven accents], and "un beso siempre tendrá el derecho de interrumpir la frase" [a kiss will always have the right to interrupt the sentence]. Watch out for "hablamos por los codos": literally "we talk through our elbows", it is an everyday idiom for talking nonstop, which is a cheeky joke in a song about saying nothing out loud.
The best line is a little wordplay on love itself: "el amor no se habla, el amor se hace" [love isn't spoken, love is made]. "Hacer el amor" means to make love, so the song is winking at you. It ends with the same idea, "mejor no te lo digo, mejor lo hago" [better not to tell you, better to just do it].