ConfigMaps & Secrets
In Portainer you can create configurations outside of a service's image or running containers. This allows you to keep your images as generic as possible, without the need to bind-mount configuration files into the containers, or to use environment variables.
A ConfigMap or Secret with the external flag was created outside of Portainer, which means Portainer has limited knowledge on it compared to one created within Portainer. A label of unused means that Portainer cannot see any applications that are using this ConfigMap or Secret. This label may also appear on external resources because of the limited information available.