Why not just read the rules?
Some cards in this expansion are both Victory cards and another type as well (Great Hall, Harem, Nobles). These cards are both types for all purposes. Great Hall and Nobles can be played like normal Actions; Harem can be spent like a normal Treasure. At the end of the game, all three contribute to your score. When a card refers to a type of card, it means any card having that type; so, for example, Adventurer will find Harems as well as other Treasure cards; Mine can be used to trade in Silver for a Harem