Ports function like “tunnels” in IDEF0.
Per VisualParadigm’s online training, at least when it comes to Component Diagrams:
A port (definition) indicates that the component itself does not provide the required interfaces (e.g., required or provided). Instead, the component delegates the interface(s) to an internal class.
So, in this case, the IdentityManagement interface provided by the Member Management component is actually provided by an internal class within Member Management.