Presumably the fear in question is fear of God? Or is it?That's not a full sentence. The full sentence, according to a google search, is: Timor carcerem inferni, mortem, et tormenta quae hostes ei minitur in gladium et ignem contra eum convertit.
This seems to mean: "Fear turns the prison of hell*, death, and the tortures, with which the enemy threatens him, into a sword and fire against him (the enemy)."
*inferni can also mean "of the depths of the earth".