Keyword difficulty is a score, from 0 to 100, that an SEO tool gives a search to estimate how hard it would be to reach the first page. It is mostly a measure of how many links the pages ranking there have. It is a tool's guess, not a Google figure, and different tools give the same search different numbers.
The number is useful for comparing searches against each other, not for predicting a date. A difficulty of 30 does not mean three months. For a local business the score often overstates the problem, because it counts the big national sites on page one and ignores the map pack, where a small business competes on reviews and proximity rather than links.
