MinRole is a new farm topology based on a set of predefined server roles introduced in SharePoint Server 2016. When configuring your SharePoint farm, you now select the role of a server when you create a new farm or join a server to an existing farm. SharePoint will automatically configure the services on each server based on the server's role. SharePoint Server 2016 has been optimized for the MinRole farm topology.

Very Detailed Explanation About Min Role in below. https://technet.microsoft.com/en-us/library/mt346114(v=office.16).aspx