Click Frequency or click rate is defined as the ratio of the number of times a given ad block (or the page that displays it) is shown and the number of times a user clicks on the advertising on that page. And since each click usually generates a small payment from Google to the publisher (in reality, a percentage of the payment that Google receives per click from the advertiser), a web-publisher could look at the click frequency as a form of conversion rate.
Conversion rate is a statistic used by most web based businesses to track the number of visitors versus the number that became customers. Based on the particular business, this number can vary widely from as low as 0.1-0.5% (for businesses that are seeking a specific targeted customer profile) to as high as 3-4% for more general category merchandisers.
As a Google AdSense web-publisher, you are offering relevant advertising to your reading public and since the only effort that a user has to do is to click on an advertisement - without any other associated cost to the user - one should expect a higher click frequency than for traditional businesses that are selling products or prospecting for customers.
Once again though, the topic of your website, the topical nature of your articles, quality and number of advertisers, all play a part in setting up your click frequency. Seasonality matters as well - you will see higher or lower clicks based on time of year (more vacations or more office hours time, holiday season or tax time, and so on). Thus, while you will see a better click frequency rate than the 1-2% rate usually seen for conversion rate - how much better it gets than that is up to a variety of factors.
To get the best results with Google AdSense though, add quality content on a regular basis, experiment a little with the location of your Ad blocks, and stick to a regular, methodical program to continue to build out your site.