Finally, the most important option is "Export Account", when you click on it, it opens a screen with three very important things about your wallet. Those three are the QR code of your wallet, your public key and your private key. It is smart to make a backup of your private key, since that is the key that gives you access to your funds that are stored in the wallet, so be wise and make multiple backups. Do not save private keys online or other places easily accessed by others.
Good to know: The private key is all you need to access your XEM balance from any other device. There is no XEM kept inside this mobile wallet app, all is on the NEM blockchain!