On the bottom section of the Overview tab, you can find the All Instances section where a list of your monitored SQL Server instances and their most important information is displayed.   

In this section, you can find the following information about your registered instances:

•  - Instance status icon. 
• Instance Name - displays the name of your registered SQL Server Instance.
• Status - displays the status of the SQL Server instance.
• # of Jobs - displays the total number of jobs on each SQL Server instance.
• # of Failed Jobs - displays the total number of jobs in which the last run outcome was failed. 
• Agent Status - displays the status of the SQL Server Agent services of the respective instance.  
• Actions - displays a  gear icon where you can Start/Stop/Restart the SQL Server Agent service. These options are available depending on the current status of your agent.