What mean the number at event end?

When you finish the event, a black screen show number 39000 something, what is that?

EDIT: I think now, that number is not present if you play the game in english, so maybe I am losing my time asking here.

it's actually three numbers - the date for Nightfall's release.

The problem is in spanish, you can read 39017 instead of release date, just bug in translation; maybe that is the number of the sentence in translation.