An Ending to Mark a New Beginning (spoilers)

[Cleretic]

Yes. He's referring to Yda's mask, which she's been using to hide the fact that she's not really Yda, she's Yda's sister. I assume you'd know this by now though, because this is only a mystery for maybe fifteen minutes of MSQ playtime; I don't know your schedule, but there's a good chance you've made time for that in the two+ hours since posting.

This is why I suggested you just keep playing the game in another thread: you're asking questions that are explained very clearly within the game itself, not long after the point where you would've been to ask them in the first place. If you've got a question like this because of a specific line that was only just said, more often than not the game will very directly answer you in pretty short order.