The Question Crosstab widget displays the frequency of each of the possible answer combinations for the two selected questions.
"Question 1: Main Question" and "Question 2: Crosstab Target Question" settings will allow you to select the two questions to show on the widget.
Drilldown functionality
Clicking on a row in the widget will open an "Evaluations" pop up window, showing you a list of evaluations that belong to the selected filtering.
Using the left PC icon will open the evaluation in a new tab of your browser, while using the right PDF icon will create a PDF of that evaluation.
Other settings
Remember to check a different help article detailing most of other settings of this widget.