Yes its quite a neat little feature. Its used to test word documents, as filler text and also to test fonts.
The first number is the amount of lines, and the second the amount of times the sentence is printed per line.
The sentence "The quick brown fox jumps over the lazy dog" is a sentence that contains all 26 letters of the roman alphabet. As such, it's a convenient test phrase when testing things like fonts and markup.
It was programmed in there by Microsoft for test text. Its similar to a "macro".
Hope this helps
source: yahoo answers