Acuarela literally translates to "watercolor". It's a beautiful and somewhat unique word to find in a reggaeton song, making it stand out.
In this song, Ozuna uses "tu acuarela es un arte" (your watercolor is an art) to metaphorically describe the unique and artistic essence of the person he's singing about. It evokes an image of something delicate, vibrant, and individually crafted, highlighting her special qualities.
"Acuarela" is Ozuna's ode to a woman he can't stop thinking about. He opens by comparing her to something almost otherworldly, an astronaut discovering a whole new view, and from there piles on playful, over-the-top compliments: she was "made for him," she deserves a Grammy, her whole vibe (down to her Van Cleef jewelry) is flawless.
The title track line, "tu acuarela es un arte" ("your watercolor is an art"), is the emotional center: he's not just attracted to her, he sees her as a work of art he can't look away from. The song stays light and playful throughout, mixing romantic lines with flashes of luxury and daily-life detail (coffee in the morning, a late night out) to paint her as someone who fits perfectly into his world.