PR3 doesn't mean the same thing as a ranking of 3, so you've used the wrong title for this thread, but it doesn't matter. As Chris pointed out, neither piece of information is meaningful.
PR3 means a page has a PageRank of 3 out of 10, but that number is a rounded off estimate of a figure that was calculated months ago and has probably changed many times since then. If it were accurate, it would be a score based on the number and strength of the links pointing to the page, which is one of many factors taken into account by Google when it ranks a page. Google has accurate PageRank data on your pages, but they're not going to share it with you, so you should ignore what you see in the toolbar.
A ranking of 3 doesn't mean anything because 1) the results you see aren't the same as what others see, and 2) that's a ranking you see for (I assume) one specific search query. It doesn't tell you anything about whether that search brings you any traffic, whether you're getting traffic for other keyword phrases, or how many times any of those searches are run.