More Than One Instance
The Quick Scan Report has detected that you are running with more than one SQL Server Instance installed on your server.
Each SQL Server Instance is a separate process that is running the full SQL Server database.
Multiple instances on the same server can be problematic unless you manage your memory and resources properly.
It is common that 2 or more SQL Server instances on the same server will end up fighting for memory or other resources. Be sure that the max server memory settings on each instance do not take up more memory than your server has available.
There are some great reasons to run multiple instances on the same server, this alert is really just there to point it out as it is commonly overlooked.
If you want to get additional details on each of the instances installed on your server you can run the SQL Server Configuration Manager to see what is running on this server.