en_tn_lite_do_not_use/isa/41/15.md

I am making you like a sharp threshing sledge ... you will make the hills like chaff

Yahweh speaks of enabling Israel to defeat their enemies as if he were making the nation a threshing sledge that will level mountains. (See: rc://en/ta/man/translate/figs-metaphor)

a sharp threshing sledge

A threshing sledge was a board with sharp spikes that someone would drag over the wheat to separate the grain from the chaff.

two-edged

This refers to the edges of the spikes that were attached to the threshing sledge. That they are "two-edged" means that they are very sharp.

you will thresh the mountains and crush them

This is a double metaphor. The mountains are a metaphor for grain, and threshing grain is a metaphor for the Israelites defeating the powerful enemy nations near them. Alternate translation: "you will thresh your enemies and crush them as if they were grain, even though they appear to be as strong as mountains" (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-hyperbole)

you will make the hills like chaff

The hills are a metaphor for the powerful enemy nations near Israel. People having the wind blow the chaff away after they have threshed the grain is a metaphor for them allowing Yahweh to destroy their enemies. (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-simile)