On this tab, you can test the search index by performing a search. It behaves exactly like a Smart search dialog with results web part using the currently edited index would.
 
Please note: You need to rebuild the index after you make any changes on other tabs for them to affect this search.
 
More resources can be found at Developer's Guide -> Modules -> Smart search -> Overview.
 

Page url: http://devnet.kentico.com/docs/6_0/contexthelp/index.html?searchindex_search.htm