Autocomplete & Suggestions -> Suggestions tab
Keyword suggestions appear when no results match the keyword.
Currently four different keyword suggestions sources are supported:
Google keyword suggestions
The search statistics database
You can multiple sources at the same time. Use the drag-and-drop box to select which sources you would like to use. The order matters.
The plugin will go through the selected sources (in order) until a keyword is returned.
The maximal keyword length is definable, to avoid lengthy suggestions. Keywords above the defined length (60 by default) will be ignored.
By default the plugins shows 10 keywords, but of course you can change that if you want.