Can refer to a brief sighting or a hint of something.
Tuve un vislumbre de lo que podría ser mi futuro si sigo trabajando duro.
I had a glimpse of what my future could be if I keep working hard.
Al caer la noche, vislumbré una luz tenue en la distancia que me intrigó.
As night fell, I caught a faint light in the distance that intrigued me.