Iron: What the rooms earn while they're running. Use Iron to upgrade the rooms and unlock new realms.
Gold: You can earn these in raids or by spending real money. You can use Gold to buy more reward chests, buy more Hammers, etc.
Shards: Duplicates of Champions, which you will use to upgrade their star rating.
Glory: Earned by defeating raids on the realm. You must cause Ragnarok to collect the Glory. Use Glory to upgrade relics on Yggdrasil, or to help upgrade Champions.
XP Tokens: Used to level up Champions, XP Tokens are earned by defending against raids. Rumble Tokens: Used in the Realm Rumble. You'll earn free Rumble Tokens a day (and more if you're a subscriber).
Hammers: Thor's Thunder allows you to cause damage to attackers in a realm. You can earn these in chests or spend Gold to activate one.