When playing live poker, sometimes cards gets mucked to your direction and possibly touch your cards. That's a dead hand (even if you have aces). Or sometimes, the dealer sees a bunch of cards in front of him/her and grabs your cards by accident which = dead hand. It protects your cards from the dealer and other cards. Also, it tells
the people at the table that you are in the current hand. Some of them are players lucky charm. Hopefully you find the right one.