The quest board allows you to complete tasks and get rewards in exchange. It features three different types of Quests.
Daily quests
These can be completed everyday to get some basic resources. Each Task gives you a certain amount of medals that fill up your quest bar. Once you collected enough medals, the rewards are unlocked and can be collected.
You do not need to complete all tasks to get all rewards.
Weekly quests
These are a little bit more complex and refresh only once per week. However, the rewards are more valuable.
Main quests
Main quests are different from the other two categories. You have to complete all of the tasks to receive their rewards and to unlock the next set of main quests.