Parameters binding and templates of Rancher Stack?

Rancher versions:
2.0

Environment Template: (Cattle/Kubernetes/Swarm/Mesos)
Cattle

What is meaning of parameters binding and templates in Rancher Stack?
https://rancher.com/docs/rancher/v1.6/en/api/v2-beta/api-resources/stack/

Can you guys give me example data of Stack with templates and binding?

Thanks!