This is an idiom. Here silence is meant to signal shock and amazement. Alternate translation: "Be shocked" (See: [[rc://en/ta/man/translate/figs-idiom]])
Here "merchant" means "many merchants." Alternate translation: "the merchants of Sidon, who travel over the sea, have made you rich" (See: [[rc://en/ta/man/translate/figs-genericnoun]])