After you open the game you can see the Main Menu:

1 - Here you can see your current level and the XP bar (how much XP you've accumulated in this level).

2 - Kisses - the premium currency of the game. You can buy Kisses with Nutaku gold or you can get them as a possible reward from events.

3 - Money - the currency of the game. You can use Money to buy various in-game items.

4 - Store - the place where you can buy various in-game items or characters. You can also access your inventory here.

5 - Save - the Save button allows you to save the game progress when you want (this is useful if you play on multiple devices and switch between them frequently).

6 - Options - this button allows you to go to Settings, exit the game, edit or see more info about characters.

7 - Character list - here you can see the available characters and if they are working on a task or are ready to start a new one.