Evidently the language is Norse, possibly an older dialect (the source I have on that doesn't seem very reliable to me).
As noted in the comments bellow, when plugged into Google Translate, the detected language is Icelandic.
Unless someone familiar with either language can confirm for sure, this is about the best I can find at the moment.
The line from the movie:
"Sem hon heldr inum helgum eignum ok krýnd í þessum helga stað ek té
fram fyrir yðr...Queen Else of Arendelle."
"As she holds the holy properties, and is crowned in this holy place,
I present to you... Queen Elsa of Arendelle."
Source for the translation.