Charles Ellicott Commentary Numbers 1:50

"but appoint thou the Levites over the tabernacle of the testimony, and over all the furniture thereof, and over all that belongeth to it: they shall bear the tabernacle, and all the furniture thereof; and they shall minister unto it, and shall encamp round about the tabernacle." — Numbers 1:50 (ASV)

The tabernacle of testimony.—The testimony, sometimes described as the two tables of the testimony (Exodus 31:18; Exodus 34:29), primarily denotes the tables of the law that were directed to be placed in the ark (Exodus 25:16; Exodus 25:21). Therefore, the ark is described as the ark of the testimony (Exodus 25:22; Exodus 26:33), and the tabernacle as the tabernacle of the testimony (Exodus 38:21). The tent, including the outer covering of the mishkan, or wooden building, is also called the tent of the testimony (Numbers 9:15). Additionally, the veil that separated the holy place from the most holy is called the veil of the testimony (Leviticus 24:3).

And shall encamp around the tabernacle.—The tent of meeting was like a royal palace, and the Levites served as a guard of honor around it, to protect it from every kind of desecration.