Federaion in GraphQL allow you to import one schema to another. You cannot see the imported nodes directly in the code editor but you can see them in the Graph view, from where you can inject them into your schema. Imported Graph library nodes are marked with a dashed line inside a Relation view.
The main benefit of using GraphQL federation s is that it allows you to reuse code, making it easier to maintain multiple schemas and keep them up to date. This is especially useful when building large, complex applications.