Golondrinas translates to "swallows," referring to the migratory birds. It's a beautiful and somewhat poetic word that isn't found in every song, making it unique and memorable.
In the context of the song, Natalia Lafourcade sings, "Hoy todas mis golondrinas van confundidas al mar" (Today all my swallows go confused to the sea). This metaphor evokes a sense of lost direction and emotional turmoil, as if her hopes or feelings, like the birds, are disoriented and heading towards an unknown, perhaps sorrowful, destination.
Natalia Lafourcade and El David Aguilar spend the whole song on a wish they never quite make good on. The title line, "Como quisiera quererte" (How I'd like to love you), keeps the verb in the conditional: quisiera, would like, rather than quiero, do. Even what they want to hand over is an hour rather than a thing. "Como quisiera entregarte / La noche, el amanecer" (How I'd like to give you the night, the dawn).
What stops them is grief that was never let out. "Es un incendio de llanto / Que no he dejado salir" (It's a blaze of tears that I haven't let out) is the bluntest line here, and the rest of the lyric keeps drifting back toward it: "Hoy todas mis golondrinas / Van confundidas al mar" (Today all my swallows go confused to the sea). So the chorus hands the job to the weather, asking the wind to carry off "lo que sufrí" (what I suffered). The song never says whether the wind agrees.