Question on Version download

[NickVM]

Decided to download the latest version at
https://www.virtualbox.org/wiki/Downloads
and saw this note:
->Please also use version 6.0 if you need to run VMs with software virtualization, as this has been discontinued in 6.1. Version 6.0 will remain supported until July 2020.<-

Excuse my ignorance, I run a VM with WinXP and one with Dos 6.22.
But I'm not sure what exactly they mean by "run VMs with software virtualization" ?
Appreciate illumination.

[mpack]

What it says. VirtualBox now requires hardware accelerated virtualization, i.e. VT-x or AMD-v, which have been available in every PC for a decade or so. Support for the old software-only virtualization engine has been dropped since usage doesn't merit the maintenance cost. If you have a decade old PC without VT-x/AMD-v then stick to the older VirtualBox version.

There are other caveats, but jump those bridges when you come to them.

[NickVM]

Thank you much, I understand now.