Dependent objects are assets that are required by other assets. For example, the connections and runtime environment used by an agent flow are dependent objects. When you export assets, you have the option to include or exclude dependent objects in the export file.
The dependent objects must exist either in the export file or in the target organization, or the import fails.
You might want to include dependent objects if they don't exist in the target organization. Or, you might want to include dependent objects if you want to replace the dependent objects in the target organization with updated versions from the source organization. If you choose to include dependent objects, the export file includes dependent objects for all of the assets that you include in the export. When you import assets, you can choose which dependent assets to import.
You might want to exclude an asset's dependent objects if the objects exist in the target organization and you don't want to replace them.