A foreshadowing I never noticed

Guys , I was studying a while ago and in the middle of the studying I remembered that Arya said to Melisandre in that scene:" you said I would shut many eyes forever, you were right about that too".. Melisandre replied: "brown eyes, green eyes... and blue eyes!" and then she gave her that look and Arya looked at her like she understood something.

Did she hint that Arya will kill the night king?! And that what aria understood? How did I not see that before, I feel like I should've gotten it once I saw it! Anybody feel like me?