The yes no element is a short cut to the having to manually set up a radio button with a standard 'Yes' or 'No' Options (represented as 1 and 0 in the underlying raw table data). It also has the advantage of automatically showing icons for the results in the list view.
Form example
List example
Administration settings
Default - should the default selected option be 'yes' or 'no'.
Options per row - (Fabrik 3.0 only) The radio button spancing
Notes
Certain Rocket Themes templates override the Bootstrap CSS we use for Yes/No, such that both buttons end up being blue, and don't change on hover / selection. You may need to add something like this to a custom CSS file in your form template: