For all Joomla 3+ templates built using the Zen Grid Framework v4 (any theme after October 2014) please refer to the Zen Grid Framework v4 documentation.
The analytics option in Zen Grid Framework compatible templates is a convenient way to include your anayltics code at the bottom of the template's index.php file.
The code will appear just prior to the closing </body> tag or the closing </head> tag depending on your selection.
Please note that you can use this feature to add any type of javascript to your template - it does not necessarily have to be Google analytics.
As can be seen in the image below, the code is simply pasted directly into the template parameter.