VMware vSan can be called as a technology that allows locally attached disks that are installed on the server to create a clustered disk space, or as Distributed Object-Based Storage. It reduces complexity eliminating the physical storage layer.
Since vSan is embedded in the hypervisor, what you need to do is only to activate it via vSphere and a separate installation is not required.
It can be taken as vSan ReadyNode from a variety of compatible vendors and make your own installation, Also can be taken as ready-to-use solutions like Dell VxRail. You can also check whether your existing hardware is vSan compliant from here and licensing for version 6.7 here