Soplido means "a puff of air" or "a blow". It's a wonderfully specific and descriptive noun that you don't often hear in songs, making it a very memorable word to learn.
In "Vivir Sin Aire", the singer desperately wishes he could forget his love, singing "Cómo quisiera borrarte de un soplido" (How I wish I could erase you with a puff of air). This poetic line contrasts the small, effortless action of a soplido with the impossible task of erasing someone from your heart, creating a powerful and poignant image.
This song from Mexican rock band Maná is built around one huge, impossible wish. The singer opens by saying, "Cómo quisiera / Poder vivir sin aire" (How I'd wish / To be able to live without air) and then, a few lines later, "Cómo quisiera / Poder vivir sin ti" (How I'd wish / To be able to live without you). He's saying that needing this person feels as essential, and as inescapable, as needing air and water to survive. Of course, he knows it's impossible. He immediately follows up with, "Pero no puedo / Siento que muero / Me estoy ahogando sin tu amor" (But I can't / I feel like I'm dying / I'm drowning without your love).
He keeps pushing this idea with more impossible images: a fish trying to swim without water, or a bird trying to fly without wings. It's a dramatic way to describe total dependency on someone. But he's also frustrated by this feeling. He wishes he could just "lanzarte al olvido" (throw you into oblivion) or "borrarte de un soplido" (erase you with a puff of air). He feels so trapped by this love that he ends with a wild line: "Me encantaría matar esta canción" (I would love to kill this song). He wants to destroy the very song that describes his feelings!