Penetration is a Bravery deck specific effect card. When used, it removes the Taunt effect from an enemy monster of your choice. If the monster you chose doesn't have Taunt, you will draw a card instead.
Both effects are particularly useful for Bravery. Removing Taunts helps get rid of opposition to Bravery's assault on the enemy player, and drawing cards always helps you to keep playing monsters
This is particularly effective against monsters with taunt that can't attack like MTT Fountain or Dog House. It also helps as a free card draw to get something more useful but at the cost of running out of cards faster.