The Azure Plugin packages cloud services and it's corresponding web and worker roles for deployment onto the Microsoft Azure Cloud Platform. It gives you far more control over the build than Visual Studio does with its built-in tools, while it utilizes the same SDK features.
It defines the packaging type azure-cloud-service and the corresponding lifecycle.
The resulting artifact is a Cloud Service Package with file extension *.cspkg; it will further attach configured variants of Cloud Service Configurations (*.cscfg) which are required when deploying to the Azure Cloud.
Have a look at the usage documentation in order to find out how it can help you in your projects.