Here the ark is spoken of as if were a person traveling. The ark was really being carried by men. Alternate translation: "Whenever the people carrying the ark stopped" (See: [[rc://en/ta/man/translate/figs-personification]])
This refers to people. The full meaning of this statement can be made explicit. Alternate translation: "many tens of thousands of people" (See: [[rc://en/ta/man/translate/figs-explicit]])