The Languages Report shows you the languages the user has installed on their computer system, so that you can determine how well you're meeting the needs of your users. To get to this report click Visitors - > Languages.
The language report looks something like the one you see on the right. T

click to enlarge
his site had 19 visits using 2 langauges, and though only 2 visits were using something other than English, it's still a good thing to know.