Five of a kind is a hand that contains five cards of one rank, such as 3&e 3&f 3&c 3&` 3 ("five of a kind, threes"). It ranks above a straight flush but is only possible when using one or more wild cards, as there are only four cards of each rank in the deck.
Basically, the rule states that you must make ten times the raise size from the total pot when set mining, twenty-times the raise size when calling with suited connectors, and thirty times the raise size from gapped suited-connectors.