Nos comió is a powerful, metaphorical phrase from the line "No sé como el tiempo nos comió" (I don't know how time ate us up).
While comer usually means "to eat," here it's used to express how time passed incredibly fast, consuming the moments the singer should have spent with his loved one. This creative expression turns a simple verb into a poignant image of lost time and longing.
This song is all about the pain and hope of a long-distance love. Junior H lays it all out, saying, "Sé que la distancia no ayuda / En el dolor que siento al día" (I know the distance doesn't help / with the pain I feel daily). He feels a deep connection with his partner, believing she knows exactly how he's feeling even when they're apart: "Sé que tú sabes cuándo yo no estoy bien" (I know that you know when I'm not okay).
He's not just sitting around feeling sad, though. The title comes from the huge effort he makes, telling her, "Viajé 1004 kilómetros pa verte" (I traveled 1004 kilometers to see you). Even though the visit can't last, he promises "No será para siempre / Un día volveré a verte" (It won't be forever / One day I'll see you again). The song ends with a powerful declaration that she is the only one for him, forever.