Bardo is an interesting slang term, particularly common in Argentina, that means a 'mess', 'commotion', or 'drama'. It's not a word you'd find in every Spanish dictionary, making it unique and memorable.
In the song, Lali sings, "Ay, que bardo que estás armando" (Oh, what a mess you're making). She uses it to express frustration with someone causing unnecessary trouble or drama, perfectly capturing the song's sassy and confrontational tone.
Lali's "KO" is a confident kiss-off to an ex who won't stop pushing. The singer used to be the one getting hurt, but she's flipped the script: "You thought you were the hunter, but you're the prey."
She calls out his empty threats and jabs at his ego, then lands the real point: he leans on her as an excuse instead of dealing with his own problems.
The chorus is where the song gets its name. Every time he tries to provoke her, the lights go out for him. It's a knockout, over and over, because she's already won the fight before it started.
By the bridge she's done explaining herself. The answer was always no, and she's not sticking around to argue about it.