The Cloud covered the Tent of Meeting, and the Glory of God filled The Dwelling.
Moses couldn't enter the Tent of Meeting because the Cloud was upon it, and the Glory of God filled The Dwelling.
Whenever the Cloud lifted from The Dwelling, the People of Israel set out on their travels,
but if the Cloud did not lift, they wouldn't set out until it did lift.
The Cloud of God was over The Dwelling during the day and the fire was in it at night, visible to all the Israelites in all their travels.