Pega la vuelta is a dramatic and forceful Spanish idiom. While it literally translates to something like "hit the turn" or "stick the turn," it's a powerful command that means "turn around and leave," or more strongly, "get out and don't come back."
In this iconic break-up anthem, the singer uses this phrase to emphatically reject her ex-lover who has returned after a long absence. It's the core message of the song, packing a punch of finality and telling him to go back exactly the way he came.
Picture this: it has been exactly "dos años y un día" (two years and a day) since Jennifer Lopez's character saw her ex, and just as she finally gets used to life without him, he knocks on her door late at night. Marc Anthony plays the wanderer who left searching for thrills and excitement ("En busca de emociones un día marché" [In search of emotions I left one day]), only to find out the grass was not greener. When he comes crawling back, admitting it was all a fake fantasy, Jennifer slams the door right in his face with a cold "Ya es tarde" (It's too late).
The chorus is wonderfully petty and direct. She tells him to "pega la vuelta" (turn right back around and leave), an everyday idiom that basically means turn on your heels and get out the way you came. She does not stop there: she orders him to forget her name, her face, her hands, and her lips. Then she delivers the ultimate burn: "Olvida de todo, que tú para eso tienes experiencia" (Forget everything, since you have plenty of experience doing that). It plays out like an intense, confrontational theatrical scene between two powerhouse voices who know how to turn heartbreak into pure drama.