The idols are described as having feelings of fear as Yahweh approaches. Alternate translation: "the idols of Egypt tremble in fear before Yahweh" (See: [[rc://en/ta/man/translate/figs-personification]])
The heart melting represents losing their courage. Alternate translation: "the Egyptians have no more courage" (See: [[rc://en/ta/man/translate/figs-metaphor]])