Possible meanings are 1) Isaiah is telling the people of Tarshish to start planting crops since they can no longer trade with Tyre or 2) Isaiah is telling the people of Tarshish they are free from Tyre's control. Alternate translation: "Pass through your land like a river, daughter of Tarshish. The people of Tyre no longer have any power" (See: [[rc://en/ta/man/translate/figs-simile]])
The "daughter" of a city represents the people of the city. Alternate translation: "the people of Tarshish" or "the people who live in Tarshish" (See: [[rc://en/ta/man/translate/figs-metonymy]])