My guess...
=rand is a function to generate "random" words, 200 is the number of words
per paragraph and 99 is the number of paragraphs to generate. (Or vice
versa; I'm not anal enough to count either. All I know is it created 235
pages of text on my system.)
Intended use: create temporary text with which to play with page, style,
font, etc formatting before actually inputing meaningful text.
Again, guesses!
Rick