en_tn_condensed/isa/10/34.md

will lop off the boughs ... and Lebanon in his majesty will fall

Isaiah speaks of the army of Assyria as if it were the tall trees in Lebanon. God will destroy the army like people cutting down the mighty trees of Lebanon. This emphasizes that though the army is strong, God has the power to destroy it. (See: rc://en/ta/man/translate/figs-metaphor)

the thickets of the forest

"the dense shrubs in the forest." This is possibly a metaphor for those people who are not well known. (See: rc://en/ta/man/translate/figs-metaphor)

Lebanon in his majesty will fall

"the forests of Lebanon will no longer be so grand." This is possibly a metaphor for the Assyrian army. Alternate translation: "Yahweh will defeat the army of Assyria, as mighty as it is" (See: rc://en/ta/man/translate/figs-metaphor)