You didn't ask me the question, but I'm going to guess the reference is to the Age of the Gentiles. An age that is about over.
Here it is in Romans 11:25:
"For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in."
That letter was written to the Romans. Who says the age of the Gentiles is over?