Estancou comes from the verb estancar, which means to stop the flow of something, like water or blood. It's a less common verb than simply 'parar' (to stop), making it more interesting.
In the song, the lyric "Mar azul também Suas ondas estancou" (Blue sea also Its waves stopped flowing) uses this word poetically to describe the sea's waves ceasing to move, mirroring the singer's emotional stagnation and the end of his love. It evokes a powerful image of stillness and loss.
Have you ever felt like your whole world lost its color after a breakup? In "Praia Nua," Jorge Vercillo paints a vivid picture of this exact feeling. The singer's lover was their "sol" (sun), and since they left, life has "escureceu" (darkened). Nature itself seems to mourn the lost love: flowers turn gray, and the vast blue ocean becomes a "poça sem cor" (colorless puddle).
At the heart of the song is a powerful metaphor: the singer sees themself as a "praia linda e nua"—a beautiful, naked beach, exposed and swept by the winds of passion. Even as they try to find comfort by looking at the moon, they admit, "meu coração é seu" (my heart is yours). It's a beautiful and melancholic song about how love can transform our world, and how its absence can drain the life from everything around us.