
Explanation:
Graphical user interface, application Description automatically generated

Box 1: Reader
Members of the Reader role can view the organization agent pool as well as agents. You typically use this to add operators that are responsible for monitoring the agents and their health.
Box 2: Service account
Members of the Service account role can use the organization agent pool to create a project agent pool in a project. If you follow the guidelines above for creating new project agent pools, you typically do not have to add any members here.
Reference:
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/pools-queues