It shows the search results of Find In Files/Replace In Files operations. It also allows the user to navigate to the desired location by just double clicking on the particular Search result in the Search window.
To view the Search Tab, go to Search > Find In Files or press the shortcut key Ctrl + D.
The following image shows the Find In Files window which appears as a result:
The search for the string VCH Value in files, displays the following results in the Search tab of Output window: