Amarga means "bitters" or "makes bitter." It's a vivid verb that goes beyond simply saying something is sad or bad.
In the song, the artist sings, "A este dolor que alarga mis noches y amarga mis días" (To this pain that lengthens my nights and embitters my days). The word powerfully conveys how pain doesn't just make his days bad, but actively sours and taints them, making them unpleasant and difficult to bear.
Have you ever felt like your past fears just keep coming back, no matter what you do? Los Rumberos totally get it in "Rumba, Sudor Y Lágrimas"! The song opens with the feeling that "todos mis miedos / Saben cada uno de mis pasos" [all my fears / Know every one of my steps], whether they're victories or failures. It's like those old worries just don't care about your progress.
But even with those fears lurking, the singer keeps trying to rewrite their story, especially when it comes to a past love. They're constantly "escribiéndote en cada verso / Y me reinvento en cada canción / Otro final para nuestro amor" [writing to you in every verse / And I reinvent myself in every song / Another ending for our love]. It's a bittersweet struggle to move on, and all that's left is "rumba, sudor y lágrimas" [rumba, sweat, and tears]. These sad tears travel down their cheeks, making the nights long and the days bitter. Even though it hurts, they can't forget that this person "fuiste el loco que amé" [was the crazy one I loved]. It's a powerful and relatable song about heartbreak and trying to find a way through it, even if it's just with some rumba, sweat, and a lot of tears.