Having statistics for your website is a high priority if you are a business. You want to know where people are coming from to track if you advertising dollars are paying off. You can also see what information people are looking for most often. Statistics answer the big questions, who, when, where, what.
Why would you want to use Google Analytics? or What data can you actually gather? Check out the Analytics Tour
Once you have your Analytics account created you can now set up your website.