VPS runs its own copy of an operating system, and customers have superuser-level access to that operating system instance, so they can install almost any software that runs on that OS.
For many purposes they are functionally equivalent to a dedicated physical server, and being software defined are able to be much more easily created and configured.
They are priced much lower than an equivalent physical/Dedicated server, but as they share the underlying physical hardware with other VPSs, performance may be lower, and may depend on the workload of other