Poker is a card game in which players wager money and place bets during one or more rounds of betting. It has many variations, but most of them share certain underlying rules. A poker hand consists of five cards. The value of a hand is in inverse proportion to its mathematical frequency; that is, the more often a particular combination of cards occurs in a deck, the higher its rank. Players may bet that they have the best hand, and other players must either call (match) the bet or concede. Players can also bluff, and can win by doing so if other players do not call their bets.
You have a pair of kings. Brad kept two cards, so he probably had a pair too. Charley kept four, and was probably trying for a flush or straight. Dennis raised earlier, so he might have been trying for three of a kind.
A straight flush is a five-card sequence in order, such as 5-6-7-8-9. It is the highest natural hand. A full house is two distinct pairs of cards matched with a fifth card (such as 5-4-3-2-A). High card breaks ties. A wild card (usually the joker) is used to fill a straight or flush, but it does not count as a high card. It is also used to break ties between two high hands.