On your 'Account' page you can update your contact information, like your Contact Number, Account name, App Language, Time Zone, etc.
The email address on this page is the default email address used to send you voicemail notifications.
The "Time Zone" setting will be used to place call and text message activity in your local time zone across all of the apps.
Also on the Account Settings page you'll see an option for "Receipt Message" and "Receipt Frequency". More info about this can be found here.
At the bottom of your Account Settings page you'll see your API Token. This is used for services, like Zapier.com, that can be used to sync your account activity with other services and apps (like CRMs).