The Templates folder holds items that you can create easily anywhere (on the Desktop, or in a file manager window), by selecting the New menu item, on the context menu (right-click menu) of the place you want the item to be.
You can put both files and directories in the Templates folder, and they will auto-magically appear in the New submenu. When you select them from the submenu, they are copied to the current location.
This is exactly like opening the Templates directory and copying the items from there directly, only it's slightly easier. By default, the Templates directory is populated with only kdelnk files. These files are here to allow you to immediately begin creating devices, programs, URL links and new mime types, but you can put anything you want here.