Bandolero literally translates to "outlaw" or "bandit." It's a word with a bit of a dramatic, old-school feel, often associated with rebels or rogues.
In this song, Corina Smith uses it to describe her ex-lover, implying he's a deceitful and untrustworthy character who has hurt her. By calling him a "bandolero," she's not just saying he's bad, but painting him as a dangerous and unreliable figure, adding a strong emotional punch to her lyrics.
"La Glock" is a breakup song about betrayal. The singer looks back at someone who swore devotion "by God," by his mother, by his father, and never meant a word of it. She calls the heartbreak a gunshot: "me disparaste con la Glock" means "you shot me with the Glock," a way of saying the lie hurt like a bullet even though nothing physical happened.
Through the verses she plays back the promises and the year she spent trusting them, only to find out he was lying the whole time. In the chorus she pushes back hard, telling him she's a ten and he doesn't even rate a zero, and that she won't waste tears crying over someone who treated her badly.
By the end she flips it around completely: she tells him that after everything he swore falsely, karma is coming for him, and she leaves him behind alone. It is less a song about heartbreak lingering and more one about calling out a liar and walking away with her pride intact.