Q. What is Microsoft Azure Backup Server?
A. Azure Backup provides a service for backup and recovery however it is primarily based around files and folders unless you utilize System Center Data Protection Manager (DPM) which adds application-aware backup and recovery services such as mailbox, database and Sharepoint item protection. Microsoft Azure Backup server is a free "light" version of DPM that provides initial protection of workloads to disk and can then store backup data in Azure Backup. Typically local disk will be used for "near" short-term backup and Azure used for longer term retention.
Azure Backup Server can be downloaded from https://www.microsoft.com/en-us/download/details.aspx?id=49170 and if you are familiar with DPM the solution will be easy to get started with and even if you are not its fairly intuitive to use. Also see Microsoft's article at https://azure.microsoft.com/en-us/blog/announcing-microsoft-azure-backup-server/ for more detail.
Note that the free Azure Backup Server does not support tape devices for longer term/offsite retention.