It means that it uses fractal math in the map generation script, exactly where I don't really know. It produces varied landmasses that are fairly random-shaped. I think it's better than what's now 'continents', where you usually get 2 pole-to-pole continents with few interesting features (and often poor water). The continents tend to be weirder than on pangea, though I think pangea with the first coast choice looks more realistic than fractal.