Ths refers to the prophesy in Isaiah 7:14 - "Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel."
I've always thought this particular prophesy the most interesting one since it tells you about the Virgin and the Son, but it does not tell you wish one is the Messiah.
That's not her name.
I can't believe I just read that.