en_tn_lite_do_not_use/jdg/06/05.md

Whenever they and their livestock and tents came up

The land of Midian was south of the land of Israel, near the Red Sea. It was common to use the phrase "came up" when speaking of traveling from Midian to Israel. AT: "Whenever the Midianites brought their livestock and tents to the land of Israel"

they would come as a swarm of locusts

The Midianites are compared to a swarm of locusts because they came in with a great number of people and their livestock ate everything that grew. (See: rc://en/ta/man/translate/figs-simile)

it was impossible to count

This is an exaggeration, a hyperbole, showing the number is very great. (See: rc://en/ta/man/translate/figs-hyperbole)