Office 365 (Groups) - SharePoint Team Sites in Groups
All Office 365 Groups come with a SharePoint team site. A SharePoint team site connects you and your team to the content, information, and apps you rely on every day.
You can use a team site to store and collaborate on files or to create and manage lists of information. On a team site home page, you can view links to important team files, apps, and web pages and see recent site activity in the activity feed.
You can access your team site from the the Site section of your Office 365 Group.
Please see this Microsoft article on SharePoint team sites for more information
Additionally, you can search the UWM KnowledgeBase for SharePoint related articles.UWM Learning TECHniques has created two SharePoint training guides: