Information about the website internal search
In the Site search section you can view various statistics about your internal site search. For example, this is when a visitor uses your internal search functionality (the search box on your website) to filter the content of your website.
PREREQUISITES: To track such information you must have search functionality on your website and you must set up site search in your Google Analytics profile.
For more information see Google Analytics Help » Set up Site Search
The Site search section contains one main report and various detailed reports located under the main report.
The following is a screenshot of the navigation on the left side of the screen and displays the structure of the information about internal search: