Chaparrita is a charming and affectionate term of endearment, literally meaning "little short one" or "shorty." It's often used to describe a petite woman in a sweet and loving way.
In this song, the artist uses chaparrita to affectionately refer to the woman he's singing about, highlighting her small stature as an endearing quality. It's a common term in some Spanish-speaking cultures, but its use here adds a personal and tender touch to the lyrics.
Standly is Chilean, Yeri Mua is Mexican, and the song is the two of them trading the same hook across that distance. He opens on a girl who will not be told what to do — "Ella no sigue la moda / Le gusta bailar sola" ("She doesn't follow fashion / She likes to dance alone") — and then calls her "Chaparrita bonita" ("Pretty shorty"), which is where the title comes from: chaparrita is Mexican Spanish for a short woman, and here it is said warmly. She takes the same melody back and answers in her own words, "Yo soy tu culoncita" ("I am your big-booty babe"), so by the second chorus the hook belongs to both of them.
The verses count the night off by the clock — "A eso de las 3 fue que la perreé" ("Around 3 is when I danced on her") — and she replies with the same hours from her own side, four and six instead of three. The last lines drop the flirting and name the collaboration outright: "Chile y México, estamos brígido'" ("Chile and Mexico, we're savage"), with brígido being Chilean slang that the Mexican half of the song has picked up for the occasion.