What are lightning component library - mock data import

Lightning library Components is the Salesforce (external) implementation of that new breed of lightweight frameworks built on web standards. It leverages custom elements, templates, shadow DOM, decorators, modules, and other new language constructs available in ECMAScript 7 and beyond. aura:import is referenced by aura:library, which is part of the underlying framework for ltng:require. It is not part of the standard Lightning components, and cannot be used by developers. If you're interested, you can read more about it in aura:library, but this only matters if you're using Aura directly, and not developing in Lightning. None of this is for importing data, it's for importing JavaScript files into components.