Retrovisor is the Spanish word for a car's "rearview mirror". It's a fantastic word that goes beyond its literal meaning in this song.
Lasso sings, "en el retrovisor, imágenes de ti" (in the rearview mirror, images of you), using it as a powerful metaphor for looking back at a past relationship. Even while driving forward in his life, he can't escape the memories of his ex that linger like a reflection.
Have you ever tried to move on from someone, but found that everything just reminds you of them? That's exactly what Lasso is singing about in "Ojos Marrones". He's on a date with a new person who seems perfect. They're at the same restaurant he used to go to with his ex, and this time, his jokes are actually landing: "a ella sí le dan risa mis chistes" [she does laugh at my jokes]. This new person gets along with his friends and they never argue. It sounds ideal, right? He even says, "es lo que siempre he querido" [it's what I've always wanted].
But there's one big problem. No matter how great this new person is, she's missing the one thing that made his last relationship special. Every time he looks at her, he realizes, "no son tus ojos marrones" [they're not your brown eyes]. The whole song is built around this simple, powerful idea. He knows the old saying, "Dicen que se supera / Un amor con otro amor" [They say you get over / one love with another love], but it's just not working for him. Without those specific brown eyes, nothing feels the same.