"In a very short time, will not Lebanon be turned into a fertile field and the fertile field seem like a forest?" NIV translation
Isaiah now shifts from his message of judgment to the promise of what is known as the Millennial Reign. We notice that he says that it will be in "a very short time" and many times we forget that, although a year or decade seems like a long time to us, in the overall time it is but a speck. Lebanon refers to a wooded mountain range on the northern border of Israel.
This mountain range (along with all others) will be brought low and made as if it was a garden. Throughout the Bible, mountains were considered as places to learn about the things of God and this speaks of the fact that, during this time, everyone will have access to the teaching of Jesus Christ. This teaching (garden) will be valued as much as a forest was valued for its lumber.
"In that day the deaf will hear the words of the scroll, and out of gloom and darkness the eyes of the blind will see." NIV translation
Isaiah goes on to explain that this time will be a time where the Jewish people will be able to understand the things of prophecy concerning the messiah. The religion will have fallen away like scales falling from the eyes. This was the same thing that happened with the apostle Paul as he accepted Jesus as the Messiah (see Acts 9:18).
"Once more the humble will rejoice in the Lord; the needy will rejoice in the Holy One of Israel." NIV translation
Once the religious scales are removed from their eyes, they will see that their efforts to create a right relationship with God can never succeed. They will have to accept the fact that they cannot get there on their own and humbly accept salvation through the grace of Jesus Christ or face judgment for rejecting Him. The needy speaks of all who see that their own efforts are not enough and they will be filled with joy at knowing that their Messiah has already done the work on their behalf.