The Real Estate screen is where you can view your current land ownership, buy a new block of land, or sell your existing. This screen will tell you how much Maximum Awake, what Garage Size, and the Cost of each block of land.
The Move House screen is where you can view the current House you have on your land. Certain houses are only available on land that is big enough. Houses will give you slight increases in the awake your land provides, so be sure to buy a house to maximise your gym trains!
Your Cars is a list of all cars you own (if any), and will give you access to modifying them, viewing their stats, and selling them.
Your Pets is a list of all pets you own (if any), and will give you access to all of their stats, attributes, and any actions they may be able to perform.
The Inventory page displays a list of all items you own, or that have been lent to you by your gang, and also displays what items you currently have equipped. From this page, you may equip any Weapons, Armour, or Shoes you may own, install parts to Cars you may own, consume items, or sell/drop any you no longer want.
Mailbox is the main mailing/communication system for the game. It will display a list of all messages in your Inbox, any Saved messages you may have, and also any messages you may have Sent.
The Events page is a listing of all recent events having occurred to you. Things you will see there more frequently are Attacks, Mugs, and Points/Money/Items sent to you, though there are many other event types.
The Referrals page lists all players you have referred to the game and provides you with an overview of their progress and when you might receive bonus points from them. It also includes a link to use when promoting or telling your friends about the game and a graphical banner you can also use.