A resource is an object in the system: Kubernetes objects (Containers, Pods, Deployments, etc), custom objects in OpenShift (Projects), or custom resources created by an installed Operator (Alerting rule). As a general rule, creating a custom object that is an abstraction or expansion of a Kubernetes concept can be confusing and is advised against (for example Projects as an abstraction of Namespaces).
Tabs are generally used to segment content: details and meta information about the resource, configurations, related settings, related objects, and child objects.
Resource role bindings:
A details panel provides a summary view of the resource and related information.