On the one hand you see the agent status, which represents the connection to your gateways and on the other hand the status of the gateway itself. Furthermore you see all supported capabilities for your environment in tabular form. In a further table all found APIs are listed. To find the APIs and other components from the gateway, you can trigger the discover here.
Discover
The basic functionality of the Discovery is explained here: Discovery
In this dialogue, you can select whether you want to discover not only APIs, but also other components such as plans, applications or subscriptions. With "Rediscover previosly ..." you can re-include APIs or components removed from the API Control Plane. Otherwise they would be ignored.
The discover dialog has different options depending on the environment capabilities.
Agent and Gateway
The current status of the connection between the API Control Plan and the agent is displayed under Agent and the connection between the agent and the environment you have set up and connected is displayed under Gateway.
If errors are displayed here in yellow or red boxes, check the agent configuration and your stored access data.