This is pretty outdated tool to cheaply generate "unique" versions of the articles in order to fool search engines in terms on "link juice". What you normally do is hire someone for $5-100[0] to write an article and manually or using a tool generate spintax version. During posting bot would simply select a random alternative from the spin list.
When Google started to use machine learning to filter out machine generated content this out this method quickly lost effectiveness. However, it is more effective on less sophisticated search engines so using this will show some benefit.
One of the more current methods is markov chain based article generation with provided keywords. And perhaps more importantly paying people to write content.
[0] With internet proliferation this has dropped substantially.
When Google started to use machine learning to filter out machine generated content this out this method quickly lost effectiveness. However, it is more effective on less sophisticated search engines so using this will show some benefit.
One of the more current methods is markov chain based article generation with provided keywords. And perhaps more importantly paying people to write content.
[0] With internet proliferation this has dropped substantially.