Learn more about Office 365 domains at https://support.office.com/article/28343f3a-dcee-41b6-9b97-5b0f4999b7ef
Learn more about Office 365 at http://products.office.com/en-us/business/compare-office-365-for-business-plans/?=SOC_YT_SMBOpt_OfficeSku_domain
To have a personalized business email address in Office 365, you set up a domain name to use with email and other services. The domains setup wizard steps you through confirming that you own the domain, making sure users with email addresses on the domain will keep getting their mail, and finally, setting up the DNS records for your domain.
With an Office 365 subscription, you can edit and create new documents on your devices. Microsoft Office 365 delivers the power of cloud productivity to businesses of all sizes, helping save time, money, and free up valued resources. Office 365 combines the familiar Microsoft Office desktop suite with cloud-based versions of Microsoft’s next-generation communications and collaboration services—including Microsoft Exchange Online, Microsoft SharePoint Online, Office Online, and Microsoft Skype for Business Online—to help users be productive from virtually anywhere through the Internet.