Automation bundles allow you to organize rules together as part of an easily exportable package. A rule operates the exact same way inside of a bundle as it does outside of a bundle, however, placing rules into an automation bundle allows you to keep them organized and use a common configuration.
When you create a bundle, you can create any number of configurable “variables” for that bundle which can be used as inputs and parameters inside rules assigned to the bundle. Those variables can then be configured by end users using a configuration form.
In short, bundle variables become a “settings” page for your automation bundle.
Whether you decide to allow users to customize a bundle variable or not, bundle variables provide a convenient way to share a common setting between multiple rules.