I’m not sure where the phrase came from or what it is, but I use it constantly:
It is either Ah, I see or Aha, sí. I say it in agreement or in slight surprise, but I’m not sure if I’m speaking English or Spanish when I say it.
Learning a new language in my late thirties has been an odd upending, full of moments when language fades into the thing beneath all language—just sounds coming out of the body, pointing.
Even stranger: my scant German vocabulary, all but ignored for the last two decades, will sometimes spill out. When I wanted to say this way (este camino) I heard myself saying diesen weg. Instead of gracioso I said lustig. Quiero came out as möchte.
Daniel says it too— Aha, sí. Ah, I see— which makes it seem real, but doesn’t explain it.