PageRank is like a rating given to your page by Google, depending on how relevant your content to the visitors is. You can also pull your PR up by building backlinks from high PR sites. Most people look at the PR number of the page to know how well it is trusted by Google. You have to understand, though, that PR is not an assurance of bringing traffic to your site and placing well in search engines results. It is stated in
Google Webmaster Central FAQ that a site's PR is not important which is why Google only do an update a few times each year. What you have to do is focus more on optimizing your site to bring traffic to it every day.