en_tn/gen/19/26.md

she became a pillar of salt

This can be translated as "she became like a statue of salt" or "her body became like a tall stone of salt."

behold

The word "behold" draws attention to the surprising information that follows.

like the smoke of a furnace

This shows that it was a very large amount of smoke. It can also be translated as "like the smoke from a very large fire."