Bandolera literally means a female "bandit" or "outlaw". It's a very dramatic and old-fashioned word that you won't hear in everyday conversation.
In this passionate salsa song, Marc Anthony uses it as an insult, calling the woman who is leaving him a heartbreaker and a thief. By calling her a bandolera, he's saying she robbed him of his love and betrayed him, adding a powerful, fiery sting to the end of the song.
This song is the ultimate 'you'll be sorry when I'm gone' anthem, delivered with pure salsa fire. Marc Anthony isn't pleading for his lover to stay. Instead, he's basically holding the door open for them, saying, "Si es verdad que quieres tú dejarme ya / Pues vete" (If it's true you want to leave me now / Well, go). He's so sure of himself that he tells them not to even bother with excuses.
He's convinced that they will never find a love as pure as his and that they are making a huge mistake. His warning is that his memory, and his music, will follow them everywhere: "Donde quiera que estés / Mi canto escucharás / Y me extrañarás" (Wherever you are / You will hear my song / And you will miss me). He predicts a lonely future for them, because, as he puts it, it's not easy to find someone "Quien ocupe mi lugar" (to take my place). It's a bold mix of heartbreak and confidence, all set to a beat that makes you want to dance.