Sure, Vbox has kernel support for guest OSes.

As far as being a hypervisor however, Vbox is strictly a type 2, i.e. it needs a host OS to run and resources are allocated to it.

In contrast, Xen and KVM are type 1 hypervisors, meaning they themselves allocate resources for guest OSes from bare metal.

There are debates about the semantics of whether KVM is type 1 or type 2 due to its implementation on top of the Linux kernel, but it is definitely in a different league than Vbox.