'Holies' in the Bible

“When the camp prepares to move out, Aaron and his sons shall come into the sanctuary and take down the veil (curtain) screening off the Holy of Holies, and cover the ark of the testimony with it;

But the Kohathites shall not go in to see the holy things, even for an instant, or they will die.”

Therefore you and your sons with you shall attend to your priesthood for everything concerning the altar [of burnt offering and the altar of incense] and [of the Holy of Holies] within the veil, and you are to serve. I am giving you the priesthood as a bestowed service, but the stranger (outsider, layman) who approaches shall be put to death.”

The Israelites shall never again approach the Tent of Meeting [the covered sanctuary, the Holy Place, and the Holy of Holies], or they [who do] will incur sin and die.