Gigante literally means "giant". It's the key word in this song's title and its most memorable line.
Bacilos sings, "Cuando yo pienso en ti, yo siento pasos de gigante" (When I think of you, I feel giant steps). This powerful metaphor creates a vivid image of an overwhelming feeling—perhaps a heart pounding like the footsteps of a giant, or the immense and approaching presence of love in his mind. It's a unique and poetic way to describe the enormous impact someone has on you.
This song is one big, beautiful confession from someone who is totally stuck on a person named Carito. He can't do anything—not laugh, not cry, not even speak—because he's so consumed by her memory. He says, "No puedo dejarte de recordar" (I can't stop remembering you) and feels like an idiot just thinking about her. The distance between them is a huge problem; she's "tan lejos" (so far away), and he feels completely powerless.
The chorus is where the magic happens. He sings, "Cuando yo pienso en ti, yo siento pasos de gigante" (When I think of you, I feel giant steps). Thinking about her is this massive, overwhelming feeling that fills him up completely. The song itself becomes his way of closing that distance. He believes that "cuando la canto yo juro que estás ahí delante" (when I sing it, I swear you are right there in front of me). It's a sweet, slightly sad admission that their paths only crossed for a moment, but what a moment it was.