Google analytics is a great tool for a webmaster to show you stats for your website (monthly viewers, unique viewers, how they got there, etc.). It is the most used analytics tool on the web and can be added to your website using a simple code. Find out more here: http://www.google.com/analytics/
Basically, Analytics is a traffic monitor. It tracks organic, paid, social, direct of referral traffic sources, the pages people land on, so on. Not until long ago it also used to show you the keywords that made people land on your site but this doesn't happen at the moment any more. Google Webmaster Tools is a great feature to complement Analytics, since it provides keywords (searches) data in relation to your website.
Google analytics is a traffic analysis tool provided by Google. it tracks the traffic for your website, it tracks browsers, locations, webpages and referring sites etc. it is also a great way to analyze and increase traffic to your website.