Any Microsoft 365 subscription that has Exchange Online and SharePoint Online will support groups. That includes the Business Essentials and Business Premium plans, and the Enterprise E1, E3 and E5 plans.
If you have an Exchange-only plan, you can still get the shared Inbox and shared Calendar features of groups in Outlook but you won't get the document library, Planner or any of the other capabilities. If you have a Yammer-only plan, you will still have the conversations feed in the Yammer group but you won't get the document library, Planner, or any of the other capabilities.
