On the home screen in Undead World: Hero Survival, the icons along the left hand side will always start with your Profile and the Shop, but beneath that, you will see a variety of rotating features. A red exclamation point will appear on an icon to call your attention to it when there is something new to see, an action to be taken, and/or a reward to collect.
Under the Events icon, you may find additional quests to complete beyond the standard Daily, Weekly, and Main Quests you can always access through the Quests menu. Some Events will feature a purchasable pass that increases rewards.
When Bingo appears, you will have an opportunity to earn additional rewards. If you do not participate in or complete Bingo, any unused Bingo tokens in your Inventory will automatically convert to Gold after the Bingo event closes.