The dcli pack command allows you to pack resources (images, config files etc) into your cli app.
Whilst flutter allows you to include assets in a dart executable no such feature exists for dart cli apps. The dcli pack command is designed to fill that void.
A resource is just a file that you want to ship with your package.
To pack a resource in you cli app create a 'resource' directory in the root of your project package.
Place each file in the resource directory.