Azure Resource Manager, as the name suggests, helps you in managing resources associated with the Azure account. It helps you in creating, updating, and deleting resources by offering you a management layer to work upon. Azure Resource Manager is a complete deployment and management service for Azure and provides features like access control, tags, locks to help you secure and organize resources after deployment.
If you wish to get started with Azure, then have a look at the Azure training course, from Intellipaat. Also, give a watch to the video on Azure Tutorial for Beginners to help you get started.