Verano rosa literally translates to "pink summer". This is not a common phrase, but rather a beautiful, poetic image created for the song to describe a perfect, idealized romance.
In the lyrics, KAROL G sings "Fuimos un verano rosa, un verano pa' no olvidar" (We were a pink summer, a summer not to forget). The color pink evokes feelings of sweetness, romance, and innocence, painting a picture of a dreamy and unforgettable summer fling.
This song is all about two people who are completely obsessed with each other after a summer romance. KAROL G kicks things off by saying she's at a party, but it's miserable because the person she wants isn't there. She's so desperate for a sign that she sings, "Estoy a ley de una señal, márcame al celular / Que estoy caliente y sin ti me voy a quemar" (I'm one signal away, call my cell / 'Cause I'm hot and without you I'm going to burn). She's tried moving on, but admits "Nadie lo hace como tú lo haces" (Nobody does it like you do).
Feid's verse is just as direct. He remembers their "verano rosa, un verano pa' no olvidar" (a pink summer, a summer not to forget) and wants to repeat it. He gets pretty specific, telling her to "alista las Duracell" (get the Duracell ready) because he wants to turn the house into a motel. The whole song is this back-and-forth of two people who are apart but thinking the exact same thing: they need to be together right now.