A Virtual Website is one that shares the same server with a number of other websites. This has the advantage of being fairly low cost as you don't have the expense of needing a server just to provide your own web and email services. The cost of the server is shared amongst the various websites hosted on it.
A potential downside to having a virtual site is that if one of the other sites hosted on the same server as your site has very heavy traffic then your website could be slowed down as a result. However, the administrator should spot any such problem and move the busy site elsewhere.
A basic site would be a typical brochure style of site with several static pages. It may have a small amount of server-side scripting for functions such as a contact form for sending information requests to the site administrator.
This would be a typical startup website for a business with the size and number of pages being dependent on the size of the company and the number of products and services that it has to offer.