Cadenas translates to "chains". It's a strong, evocative word that immediately brings to mind images of confinement and struggle, making it quite memorable.
In the song, the lyrics "Romper las cadenas del tiempo y no dejarte partir" (Break the chains of time and not let you leave) use "cadenas" metaphorically. It represents the constraints of time and circumstances that threaten to separate the lovers, and the desire to overcome them to stay together. This powerful imagery adds a dramatic flair to the romantic theme.
La Santa Cecilia keep circling one night they can't let go of. It opens deep in the narrator's own head: "En la locura de este pensamiento" ("In the madness of this thought"), chasing "el recuerdo de aquellos besos" ("the memory of those kisses"). They want to "Romper las cadenas del tiempo y no dejarte partir" ("break the chains of time and not let you go") -- a pretty blunt way to admit they'd stop time if they could. The whole chorus is just one line on repeat: "Ella me enamoró aquella noche" ("She fell in love with me that night"). No bridge, no twist, just that night looped, close enough to still feel it: "Tu cuerpo tan cerca al mío bailando así" ("Your body so close to mine dancing like this").