Shows you how your link profile compares to leading competitors. Link quality tends to matter much more than link quantity. Ranking near the top of the search results is self reinforcing. When people create various automated spam sites or legitimately reference sites they are far more inclined to reference sites at the top of the results than sites which are nowhere to be found. It can take a year or more to build up a competitive quality link profile in competitive marketplaces.
Please note that Google only shows an exceptionally small sample of the linkage data they know of. Some of the other engines show a much larger sample. Google still counts many of the links they do not show when you do a backlink check on Google, but due to algorithms like TrustRank Google seems harder to manipulate than Yahoo! or MSN using techniques like bulk low quality link spam.