vRealize Automation is, as VMware puts it, cloud automation software. It’s the black box where the magic that happens between a customer or consumer of your cloud services and the infrastructure the cloud sits on, providing the services we would normally associate with a cloud service such as self-service, elasticity and multi-tenant support.
In the past, this product was known as vCloud Automation Center, or vCAC. It was rebranded along with a number of other VMware products under the vRealize banner. However, the newly branded vRealize Automation product still retains some references to vCAC.