Cotizarse literally refers to pricing something or being quoted on a financial market, but in Spanish slang, it means to play hard to get or intentionally boost your personal value.
In the lyrics, Shakira sings that the other woman "se hace la bruta pa' cotizarse" (plays dumb to raise her stock). It is a clever, engaging verb that highlights how Spanish creatively uses business terms to describe dating and romantic games!
Shakira is not messing around in this song! She jumps right into a love triangle, telling the story from the perspective of a woman who is absolutely sure she's won. She calls herself "loca con mi tigre" [crazy for my tiger], and she's talking to the man she wants, who is currently with another woman. But Shakira's character isn't worried. She sees the other woman as someone who plays games and acts "bruta pa' cotizarse" [dumb to make herself seem more valuable]. Meanwhile, she's just waiting, confident that what's meant for her will be hers, saying "lo que está pa' mí / Ninguna va a poder quitármelo de un tirón" [what is for me / no one can snatch it away].
She paints a very clear picture of why she's the better choice. While the other woman buys him things and caters to his whims, Shakira offers adventure and passion. The other girlfriend is so jealous that she supposedly "anda con un rifle" [walks around with a rifle] because she saw Shakira dancing for him. The best and most direct line has to be: "Mientras él te compra flores, yo compro condones" [While he buys you flowers, I buy condoms]. It's a bold, funny, and confident declaration that she offers a different, more exciting kind of connection.