This latin acronym is very famous in the alchemical world. It means : Visit the interior of the Earth, and by rectifying, you will find the hidden stone, universal medicine, sometime it is true (Veritam) medicine, but it is a U and not a V, so I prefer to say "universal".
First of all, we have to visit, not to take something, not to do something, nor seeking for something, but, just to look, to visit the interior of the earth. We have to look deeply at something hidden normally (the interior of), the earth is here the macrocosm and all its microcosm, earth can be understood as a general term for the world and the creation, Nature. So, we have to unveil the laws and mechanisms of the macrocosm.
The first part is the study.
Then we have to rectify, we have to do an action, upon something, in order to have the Stone.
Rectifying is a correction, rectification : to make it right, perfect, able to fit to the purpose of the generation of the Stone. What do we have to rectify, and what do we rectify while visiting the Nature if not our vision of the World and Nature ?
And then, we find the hidden Stone, universal and true medicine ! We find it because we are in the natural path, and no more a cultural one, that prevents us to see and find the Stone (and generate it). It is hidden because it is everywhere, and no one can see it, until one finds it by rectification.
But, in reality, we rectify and then we find the Stone, because it appears after the act of rectification, it appears as a natural consequence, we have to do nothing ! (see Aurora of the Philosophers by Paracelsus, chap XVII).
It is Universal, simply because the Mercury is Universal, and the Vitriol is our Mercury. And it is a medicine, because Light incarnated is the most important thing on earth, it is a blessing, the true blood and body of Christ Principle.