A Minimum Viable Solution (MVS), as the term suggests, is the minimum you can invest in order to reveal and demonstrate what a solution is and is capable of, or, as Ash Maurya wrote in Scaling Lean, “[a]n MV[S] is the smallest solution that creates and captures monetizable value from users.”
For a website, maybe the MVS is a landing page and dropdown lists etc., but you don’t have the backend program, a backend database attached, or credit card facilities yet. If you’re thinking of starting a restaurant, maybe the MVS is walking down the high street in themed costume with a platter of giveaway samples – next time you do the same but try to sell the samples.
In all cases, the MVS is used to solicit interest, feedback, and hopefully sales, or at least cash-up-front orders. You achieve this by showing prospects what the MVS looks like and how it functions, within the limits of the MVS since it is not by definition complete, or fully functional. You use the feedback received to improve the MVS, and you repeat, either until you have a very high confidence that your MVS is ready for launch, or that no one is interested, or there will not be enough Customers, or Customers will unlikely pay you what you need, in which case you either pivot or abandon.