en_tn/jer/46/21.md

soldiers in her midst are like a fattened bull

The writer compares soldiers to "fattened bulls" because the soldiers are well cared for by the Egyptians just as a farmer takes care of a bull and makes it fat. (See: rc://en/ta/man/jit/figs-simile)

They will not stand together

To "stand together" is an idiom meaning to remain united. The writer is saying that the soldiers will not fight as a unit but will run away thinking only of saving themselves. (See: rc://en/ta/man/jit/figs-idiom)

the day of their disaster is coming against them

This speaks of a day as if it travels and arrives in a location. Alternate translation: "they will experience disaster on that day" (See: rc://en/ta/man/jit/figs-metaphor)