"NAP" stands for Name, Address, Phone Number. Having accurate and consistent NAPs is likely the single most important component of effective local SEO. This is one of the reasons small business owner can not take a NAP, they are spending a lot of time fixing their NAP.
While almost all business owners want to win in local search, studies have shown that, aside from their own websites, the majority of businesses never update their NAP information online. Most say they don't have the time and resources to hunt down all of their online listings to find and correct mistakes.
This puts a lot of businesses at a disadvantage. Most surveys lists "Accuracy of Address" as the #1 positive factor in local search and "mismatch NAP" (i.e., between different directories) as the #3 negative factor. Stated another way......
Even if your NAP is accurate, inconsistencies can be regarded as "mistakes" by search engines. For example, if your address is listed as "123 - 301 2nd Street" on your website, but uses different variations such as "301 2nd St., #123" on Yelp, "301 Second Street, Suite 123" on Foursquare, etc. search engines will likely penalize your ranking.
If you're in this situation, or worse, if you have modified your business name, moved, or changed your phone number, then it may be time to do some remediation. Track down every one of your local listings, and make sure they are accurate and consistent.
Achieving good local SEO can be hard work. However, when you consider the number of business that doesn't bother fixing their NAP, the payoff for this investment can be substantial.