On occasion, you may want to re-purpose an existing SharePoint 2013 site. Creating a site template allows you to create new sites based off the template. You can choose to either include existing content or to simply use the site's structure.
Go to Site Settings > Save site as template
Name your template and indicate whether or not you want to include the content or just save the structure
Then press OK
It DOES take a little while so don't be concerned
Go to the site contents of the site where you want to create this site and click new subsite
Name your site and under the template section choose the
Custom tab and then choose the template that you just saved.
with any site creation, choose the permissions and navigation, then click Create
That's all there is to it!!