Sostén translates to "support". While it can mean physical support, in this powerful ballad it describes something much deeper: a person who is your emotional rock and foundation.
Christina Aguilera sings, "Eres mi protección, mi sostén frente a todo" (You are my protection, my support in the face of everything). It's a beautiful, poetic word that captures the feeling of having someone who keeps you strong, no matter what.
This is a huge love song! Christina Aguilera is singing about someone who is her absolute rock. This person is her strength when she feels like she's about to fall, or as she puts it, "Cuando estoy por caer / Yo sé que tu amor me volverá a socorrer" (When I'm about to fall / I know your love will come to my rescue again). It's a song about a love that's so powerful it helps her overcome fear and gives her life meaning.
She describes this person as her everything: "Mi protección / Mi sostén frente a todo, mi mejor opción" (My protection / My support against everything, my best option). They are her light in the darkness, her courage through the worst times, and the reason she is who she is. It's a beautiful tribute to finding that one person who feels like a safe home you can always return to.