Anclada is the feminine past participle of the verb anclar, which means "to anchor". It's a wonderfully poetic word that you don't often hear in everyday conversation.
In "Amarillo", Shakira sings "Estoy perdida, vivo anclada a ti" (I'm lost, I live anchored to you). She uses this powerful image of an anchor to describe a deep, immovable emotional connection to her lover, suggesting stability and a feeling of being completely devoted.
Have you ever been so in love that it feels like you're seeing in new colors? That's exactly what Shakira is singing about in "Amarillo." She's completely captivated by someone, asking, "¿Qué será lo que fabricas tú? / ¿Lo que te hace tan especial?" [What is it that you make? / What makes you so special?]. She feels totally attached to this person, comparing herself to "un pájaro a su cielo azul" [a bird to its blue sky]. She even throws in a little "T'estimo," which is "I love you" in Catalan, a language spoken in parts of Spain.
The whole song is built around a fantastic color metaphor. Her lover's affection is an "arcoiris de colores" [rainbow of colors], and each one represents a different part of their relationship. Yellow means "me tienes en los bolsillos" [you have me in your pockets], while purple means "ya me olvidé del pasado" [I've already forgotten the past]. It gets pretty dramatic with red, where she says her eyes bleed from crying when they're apart—a very intense way to say you miss someone! It's a song about being completely overwhelmed by love, seeing your whole world through the lens of one amazing person.