en_tn_lite_do_not_use/jer/46/23.md

They will cut down the forests ... although it is very dense

This continues speaking of the enemy army attacking the Egyptians as if the army were woodcutters cutting down trees. Alternate translation: "The enemy army will kill many Egyptians like woodcutters cutting down a forest ... even though there are very many trees" (See: rc://en/ta/man/translate/figs-metaphor)

this is Yahweh's declaration

Yahweh speaks of himself by name to express the certainty of what he is declaring. See how you translated this in Jeremiah 1:8. Alternate translation: "this is what Yahweh has declared" or "this is what I, Yahweh, have declared" (See: rc://en/ta/man/translate/figs-123person)

locusts

This is a type of insect that travels in very large groups and can cause great destruction by eating crops.

unable to be counted

This can be stated in active form. Alternate translation: "no one will be able to count them" (See: rc://en/ta/man/translate/figs-activepassive)