hubieras ido is a form of the verb ir (to go) in the past perfect subjunctive. This special mood is used to talk about hypothetical 'what if' situations in the past that didn't happen.
In this iconic song, the title itself, "Si no te hubieras ido..." (If you hadn't gone...), sets a tone of deep regret. The singer uses this phrase to imagine how happy his life would be, creating a powerful and heartbreaking contrast with his current reality of loss.
If you have ever felt completely stuck while the rest of the world just keeps moving, Maná knows that exact pain. In this classic Mexican rock track, the singer wakes up and faces a routine that feels totally broken without his partner. He even looks at his reflection and says, "El espejo no miente, me veo tan diferente" ("The mirror does not lie, I look so different"), showing how deep loss physically changes how we see ourselves. Outside his window, "La gente pasa y pasa" ("People pass and pass by"), but normal everyday life just feels wrong now.
The emotional core of the track comes down to the title line itself: "Si no te hubieras ido sería tan feliz" ("If you had not gone, I would be so happy"). That conditional phrasing is a textbook way to express regret in Spanish. He takes the ache even further with a dramatic, almost theatrical line: "El frío de mi cuerpo pregunta por ti" ("The cold of my body asks for you"). It is blunt, heavy, and very honest about the brutal waiting game of missing someone when you have no idea where they went.