Resources, more commonly but unofficially known as "stars", are displayed at the top of your screen. Stars are also the unit of measure for resources. They are the game's official currency, used for actions such as training units, buying technologies, harvesting resources (such as animals, fruit, fish, ores), and building structures such as ports and temples. The Reward "Resources" is unlocked after upgrading to a level 3 city and awards you with 5 resources. You will automatically get resources each turn. The number of resources produced each turn will depend on the amount of cities you have and can be seen at the top of the resources space.
Be warned, though, that resources and resource production are different things. Some actions, like Chopping Forest, Whaling or selecting the Resources when upgrading a level 2 city to level 3 return plain stars, whereas others like building Customs Houses or selecting workshop when upgrading a level 1 city to level 2 will increase overall star production per turn.