Page impression and page views are interchangeable -- they both refer to how many times a page has been viewed by a user. One user can visit a site and generate 10 pageviews, meaning they went through 10 pages of the site before leaving.
Pageviews is an indicator of a site's stickiness, giving you an indication whether your content is of interest to a user. You look at pageviews especially relative to visitors: e.g. 100,000 pageviews from 10,000 visitors mean your ratio is 1:10.
On average, the user views 10 pages of the site. If your ratio of visitors to pageviews is only 1:1, then it means that people are only going to a single page. Then you need to look at whether the problem lies in your navigation (they can't move from that page to another page of your site); or whether you need to rethink and polish your content; or you need to improve the aesthetics and layout of your site.
There are a number of site metrics in addition to pageviews that are important.