You may wonder what is entering metadata into VirtueMart all about or if you have not prepared metadata please take a look at the Writing great metadata recipe When your ready to go read on.
At the risk of repeating myself if you have completed the Entering your metadata in Joomla! recipe, the key to having a highly effective metadata is to specifically tailor it to each and every product as well as each product category.
Each page crawled by Google will then have precisely the right metadata to match the contents. Google will notice the continuity and your search rank for the page might improve because of it.
But even more than this is people searching for your products or range will see your meta ...