This plug-in is mostly of interest to Swedish, Norwegian, and Danish authors.
Lixtal calculates the readability index of your entry, the so-called "LIX-tal," which is a simple measure of the complexity of your text. As the Lixtal increases, the text will appear harder to read.
You can use to plug-in to get an indication of how well your written communication corresponds to your target audience. Note that the metric makes sense only for the Scandinavian languages.