en_tn_condensed/isa/23/03.md

Upon the great waters was the grain of Shihor

"The men traveled on the large sea to transport the grain from Shihor in Egypt"

the harvest of the Nile was her produce

The "harvest of the Nile" refers to the grain that was harvested near the Nile River and transported on the river and then to Phoenicia.

it became the commerce of the nations

"you were where people from other nations came to buy and sell goods"