The “Holy of Holies” (also called “the Most Holy Place” or “the Holiest of all”) was the innermost part of the tabernacle and later, the temple. It was so sacred that only the high priest could enter it and then only once a year.
When Jesus died, the veil (which was very thick, more akin to a wall) in the temple around the Holy of Holies was torn in two, from top to bottom. This is significant for two reasons:
First, being torn from the top down signifies that it was God’s doing. Since it was 30 feet high, a person would only be able to tear it from the bottom up. In effect, God was saying, I’m changing the old way of doing things.
More importantly, this opened up the Holy of Holies, showing that everyone could now approach God, at any time — not just the high priest once a year.
Jesus changed things indeed, making it possible for all us to directly approach God.