Now in that first covenant between God and Israel, there were regulations for worship and a sacred tent here on earth.
There were two rooms in this tent. In the first room were a lampstand, a table, and loaves of holy bread on the table. This was called the Holy Place.
Then there was a curtain, and behind the curtain was the second room called the Most Holy Place.
In that room were a gold incense altar and a wooden chest called the Ark of the Covenant, which was covered with gold on all sides. Inside the Ark were a gold jar containing some manna, Aaron's staff that sprouted leaves, and the stone tablets of the covenant with the Ten Commandments written on them.
The glorious cherubim were above the Ark. Their wings were stretched out over the Ark's cover, the place of atonement. But we cannot explain all of these things now.
When these things were all in place, the priests went in and out of the first room regularly as they performed their religious duties.
References for Hebrews 9:6
But only the high priest goes into the Most Holy Place, and only once a year, and always with blood, which he offers to God to cover his own sins and the sins the people have committed in ignorance.
By these regulations the Holy Spirit revealed that the Most Holy Place was not open to the people as long as the first room and the entire system it represents were still in use.
This is an illustration pointing to the present time. For the gifts and sacrifices that the priests offer are not able to cleanse the consciences of the people who bring them.
For that old system deals only with food and drink and ritual washing -- external regulations that are in effect only until their limitations can be corrected.