This song is built around a lighthouse, and its big idea is a surprise: "No es la luz lo que importa en verdad, son los 12 segundos de oscuridad" (It's not the light that really matters, it's the 12 seconds of darkness). A lighthouse beam turns, and sailors recognise each lighthouse by its pattern of flashes and dark gaps. So the darkness is part of the signal, not a failure of it.
Drexler pushes it further: "Un faro quieto nada sería" (A lighthouse standing still would be nothing), it only guides "mientras no deje de girar" (as long as it keeps turning). And "De poco le sirve al navegante que no sepa esperar" (It's little use to a sailor who doesn't know how to wait). You can hear it as a song about getting through hard stretches of life, step by step, "pie detrás de pie" (one foot after the other). The writing is spare and calm, and the tick of those twelve seconds is lovely to learn along with.