A WLAN template is a collection of WLAN policies, Tunneling Policies and WxLAN policies. WxLAN is the Mist Policy Engine which is covered later.
WLAN Template example
The benefit of a template is the same configuration can be applied to multiple sites or site groups or the entire organization. Local site configs can be added as well but the over arching template or templates remain.
Templates are very useful for automation, but not really if there is only 1 site
For example a guest template could be created with a WLAN, a tunneling policy and a WxLAN policy and applied to the entire org. Every AP in the Org will now publish that guest WLAN.
Another example would be an IoT template. This could again contain everything to enable IoT and be tied to a site group called IoT – as a new site deployed the particular IoT devices that site would be joined to the site group and the IoT WLAN would be instantly available.