When you search for a product or service that you can get locally you've most likely noticed the little side panel that pops up. These are Google My Business listings and they're the cornerstone of local SEO.
Good local SEO will make you stand out from the pack by placing you at the top of the results when someone makes a search for something they want to get locally.
You'll want to fill it out as completely as possible but the real value lies in the reviews that come in. These increase your SEO power, making you one of the three or four businesses that show up in the side panel before you get to the real search results.
It's a valuable position to put yourself in but you'll need two things: a good average rating and a lot of reviews to get there.