For 5G, both you and your enemy will skip the next turn. Monster and passive effects will still work, and both players still obtain gold and draw a card, but neither can use a card or attack with their monsters for 1 turn.
This is useful to gain some cash or clog the enemy's hand. It can also be used if the enemy has one monster which will be un-paralyzed the next turn. Using this blocks the enemy to use that monster while un-paralyzed. It will then be paralyzed again on your next turn, unable to be used by the enemy the turn after that. This essentially makes the enemy monster paralyzed for 3 turns in a row with just 1 card.