Microsoft has a ton of information regarding SharePoint governance. Considering that it’s such a broad subject, lots of documentation is good. The challenge is finding the most important bits.
The article that provides the best overview is Microsoft’s Technet article What is governance on SharePoint 2013? A related TechNet article is Governance planning on SharePoint 2013.It includes a download of one of my favorite Microsoft SharePoint governance resources: the huge overview image that shows how to tie it all together (see it on ZoomIt). Microsoft made one of these for SharePoint 2010 and possibly for SharePoint 2007. It has evolved as the product has matured but is a fantastic resource.