Office 365 is a set of subscription-based software plans from Microsoft that include access to Office applications plus other productivity services that are enabled over the Internet (cloud services), such as Lync web conferencing and Exchange Online hosted email for business, and additional online storage with OneDrive and Skype for Business.
There are several Plans available, with the Office Business Premium plan being best suited to your business needs, and benefits from the following features:

Always have the latest versions of:
Word, Excel, PowerPoint, Outlook, OneNote, Publisher, Skype for Business

Office on PCs, tablets, and phones

Enjoy a fully installed Office experience across PCs, Macs, Windows tablets, iPad® and Android™ tablets, and most mobile devices. Each user can install Office on 5 PCs or Macs, 5 tablets (Windows, iPad, and Android), and 5 phones.

Email and calendars

Use business-class email through a rich and familiar Outlook experience you can access from your desktop or from a web browser using the Outlook Web App. Get a 50 GB mailbox per user and send attachments up to 150 MB.

Online conferencing

Host online meetings with audio and video using one-click screen sharing and HD video conferencing.

Corporate social network

Connect with other Skype for Business users via instant message, voice calls, and video calls, and let people know your availability with your online status. Share presence, IM, and audio calling with Skype users.

Corporate social network

Yammer collaboration software and business applications allow your employees to connect with the right people, share information across teams, and organize around projects so they can go further, faster.

Office Online

Create and edit Word, OneNote, PowerPoint, and Excel documents from a browser.

File storage and sharing

OneDrive for Business provides 1 TB of storage for each user for virtually anywhere access to their documents. Share files with others inside and outside your organization, control who can see and edit each file, and easily sync files with PCs/Macs and devices.

Team sites

Enable easy access and sharing of documents with 10 GB baseline storage plus 500 MB of storage per user.

Search and discovery

Stay in the know. Search and discover content across Office 365 based on personalized insights. Office Delve is the first experience to be powered by Office Graph, a collection of analysed signals or insights derived from each user’s behaviour and relationships to content, topics, and contacts.

Reliability

Get peace of mind knowing your services are available with a guaranteed 99.9% uptime, financially backed service level agreement (SLA)

Security

Cutting-edge security practices with five layers of security and proactive monitoring help keep customer data safe.

Privacy

Your data is yours. We safeguard it and protect your privacy.

Up to date

No need to pay for version upgrades; updates are included in your subscription. New features are rolled out to Office 365 customers regularly.

Active Directory integration

Manage user credentials and permissions. Single sign-on and synchronization with Active Directory.

Support

Microsoft Support provides telephone and online answers, how-to resources, and connections with other Office 365 customers for setup and quick fixes.