This is from wikipedia. Sort of self explanatory.
A page view (PV) or page impression is a request to load a single page of an Internet site. On the World Wide Web a page request would result from a web surfer clicking on a link on another HTML page pointing to the page in question. This should be contrasted with a hit, which refers to a request for a file from a web server. There may therefore be many hits per page view.
These page views may be counted as part of web analytics. For the owner of the site this information can be useful to see if any change in the page (such as the information or the way it is presented) results in more visits. If there are any advertisements on the page, the advertisers would also be interested in the number of page views to determine their expected revenue from the ads. For this reason it is a term that is used widely for Internet based marketing and advertising.