#she became a pillar of salt

Because she disobeyed angel who told them not to look back at the city, God caused her to become something like a statue made out of rock salt. AT: "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. AT: "like the smoke from a very large fire" (See: [[:en:ta:vol1:translate:figs_simile]])