King James Version
And when the camp setteth forward, Aaron shall come, and his sons, and they shall take down the covering vail, and cover the ark of testimony with it:English Standard Version
When the camp is to set out, Aaron and his sons shall go in and take down the veil of the screen and cover the ark of the testimony with it.New International Version
When the camp is to move, Aaron and his sons are to go in and take down the shielding curtain and cover the ark of the Testimony with it.