Penetration is a Bravery deck specific effect card. When used, it removes the Taunt effect from a monster of your choice, including your own. If the monster you chose doesn't have Taunt, you will draw a card instead.
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.