en_tn/isa/11/15.md

the gulf of the Sea of Egypt

A "gulf" is a large area of water that land partly surrounds.

With his scorching wind he will wave his hand over the Euphrates River

Waving his hand over something represents his power to change it. Alternate translation: "By his power he will cause a scorching wind to blow on the Euphrates River" (See: rc://en/ta/man/jit/figs-metaphor)

his scorching wind

This is a strong or hot wind that causes some of the water in rivers to dry up.

so it can be crossed over in sandals

"so that people can cross over it even while wearing their sandals"