So it was, whenever the ark set out, that Moses said: “Rise up, O LORD! Let Your enemies be scattered, And let those who hate You flee before You.” And when it rested, he said: “Return, O LORD, To the many thousands of Israel.”— Numbers 10:35-36 NKJV
The ark is the Ark of the Testimony. As I have written before, this is the container that held the items which were things that testified of G-d. The Ten Commandments, G-d’s Word, Aarons staff, G-d’s Power, and the Omer of Manna, G-d’s Provision.