1)
What do we learn from "Yamim Rabim"?
1.
Rashi: The Nevu'ah will be fulfilled only after a long time.
2)
Why does it mention both "Yamim Rabim" and "Itim Rechokos"?
1.
Malbim: The Chazon (vision) is for many days from now. Also the Nevu'ah (his mission to tell the people) is for a distant time.