This computer doesn't have VT-x/AMD-v enabled. Enabling it in the BIOS is mandatory

VirtualBox does not support nested virtualization, so the guest VM will not support VMX or SVM even though the host machine does. You can't run a VM inside a VM.

From your screenshot, it looks like you're trying to run Kubernetes in your VirtualBox VM. I'm not a Kubernetes expert, but my understanding is that it's meant to manage a cluster of virtual machines. The lack of nested virtualization means you can't run the cluster within a VM; you have to install it on real hardware. Basically, Kubernetes is something you'd use instead of VirtualBox, as a different way of creating and managing your VMs.

If you really need to run Kubernetes in a VM, VMware Workstation and Player seem to support nested virtualization.