# They will pick up bows and spears

"The soldiers will carry bows and spears"

# Their sound is like the sea roar

"The sound that they make is very loud, like the sound of the sea"

# they are riding on horses, set out in order as men for battle

"they are riding on horses in their assigned rows, and they are ready to fight"

# daughter of Babylon

This refers to the Babylonian people.