When enabled, a Reset button is displayed within the front-end settings (filters) area.
By default the button will reset the search settings to the default, then do nothing. With the functionality swtich, this behavior can be changed.
The button is printed to the same block where the "Search" button is (if visible). This option lets you change if it should be before or after the search button.
The visual options let you change the text, alignment, colors, fonts an other button settings. Clicking on the button or the Select a button theme link, you can choose from pre-defined button themes as well.
By default the reset button is positioned as last in the filters list. It however depends on the filters layout as well.
To change the buttons position, navigate to the Frontend Search Settings -> Advanced Menu, where you should see a drag & drop type option. On the bottom of it, you should see the search_button item. Dragging it will change it's position.
The buttons position may also be affected by the column layout. This layout can be changed on the Frontend Search Settings -> General panel.