As the size and complexity of real-time 3D productions increases, and as the number of tools that make up a modern production pipeline continues to grow, adding intelligent automation to increase artist efficiency becomes ever more critical. This intelligent automation typically relies heavily on metadata: custom-defined properties about your Assets that give them meaning within your project.
An artist or creator adds metadata properties in one application, typically where the Asset is first created. The metadata then stays associated with that Asset, and applications farther down the pipeline can read that metadata and use it to make decisions about how to process or handle that Asset.
In the Unreal Editor, you can set and retrieve metadata keys and values for your Assets using Blueprints or Python scripting, as explained on the Asset Metadata page. This can help you with any Asset management operations you carry out solely within the context of your Unreal Project.
However, the real value of having metadata on Assets typically lies in interoperability with external applications, and in the ability to create larger Asset management pipelines that span multiple applications. To this end, the Unreal FBX Importer brings in certain kinds of Asset metadata from FBX files and makes that metadata available inside the Unreal Editor.
Note: Because this metadata is assigned to the Assets in your Project, you can't access it directly in your runtime gameplay code. It is intended primarily for use in the Unreal Editor, for scripting Asset management operations.