Manuk Coins are coins that are earnt thought completing certain quests from various NPCs. some of which are repeatable while others can only be done once per character
Completeing the following quests will give you Manuk Coins
(Will make this a table once i have tried all ways)
Fifteen From Two Tribes Quest (One Time)
Coins can currently be used by going to Manuk and heading East to a big building. in the building will be an NPC called Merchant of Manuk (You will need the Ring of Wise Kings to talk to the npc) . you can exchange one Manuk Coin for of a choice of three foods. Manuk's Opportunity ,Manuk's Courage and Manuk's Faith.