Kamas are the main currency in Dofus.
Kamas have no weight, meaning a player can carry millions of Kamas as easily as he can carry ten, however 1 trillion Kamas is the maximum amount of Kamas one can have in his inventory. The symbol for Kama is a styled 'K'. Any NPC or other game price using K means Kama.
The suffix 'k' (short for 'kilo') means 1000 of something if it refers to an object ('10k wheat' means 10,000 wheat). When it refers to the currency, a k is used to represent normal units and double k ("kk") is used to indicate that the item price is thousand. For example, someone buying a Tofu Feather for 20k means they're looking to spend 20 kamas on it. Whereas if they had said 20kk it would have meant 20,000 kamas.
However, if someone were to sell an item for '1.4mk' this would mean 1,400,000k. MK means Million Kamas, '1.4bk' would mean 1,400,000,000k, and so on.