«The lion, which is the mightiest among beasts»: «Mightiest among beasts» is literally “a mighty one among beasts.” Good News Translation “strongest of all animals” expresses this well.

«And does not turn back before any»: This means essentially the same as the previous line. «Does not turn back» may be taken to mean “is not afraid of” or “does not run away from”; so Good News Translation has “afraid of none,” Contemporary English Version “fearless,” and New International Version “who retreats before nothing.”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Proverbs. (UBS Helps for Translators). New York: UBS, 2000. For this and other handbooks for translators see here .