Backlink
A link from another site to yours. Google counts them as recommendations and they are among the heaviest factors for ranking.
The idea is simple: if many sites link to yours, Google assumes you have something worth linking to.
For a local business the ones that work are close and real: the chamber of commerce, the neighborhood paper, the supplier who lists you as an authorized installer, your trade association. One of those beats fifty bought links.
Packages selling '500 links for $50' do damage and cannot be fully undone. It is one of the few things in SEO that can leave you worse off than before.
What to do about it
Make a list of five real sites in your city or trade where you could be listed, and ask to be listed. Without paying.
Other words about the same thing