When you install the Checklist app, the Checklist Read-Only Proxy custom field type will also become available in your installation.
This custom field type reads the data from the Checklist custom field and displays progress information based on the status of the checklist. It can be rendered in different visual formats, such as a banner or progress bar, which is very useful on Agile cards. You can even customize the proxy to display your own text.
First, though, you first need to add a Checklist Read-Only Proxy custom field to Jira and configure it to suit your needs.
To get started, proceed to Adding a Proxy custom field.