Five of a kind is a pokerhand such as A♠ A♣ A♥ A♦ (Wild), which contains five cards of the same rank (only possible in wild card games). It ranks above all other poker hands.
Higher ranking sets of five defeat lower ranking sets. (If this ever comes up in your game, you are playing with way too many wild cards).
External link
Winning Poker Hands (http://www.pokerspy.co.uk/help/winning_poker_hands.php/)
In games where more than five cards are available to each player, hands are ranked by choosing some five-card subset according to the rules of the game, and comparing that five-card hand against the five-card hands of the other players.
An additional hand type, five of a kind, exists when wild cards are used.
Five of a kind outranks the straight flush (and therefore the royal flush too) making it the most valuable hand.