You can verify a business listing on Google in multiple ways, although some options differ depending on your type of business and region. This infographic from SE Ranking will show how to verify a Google My Business listing with a postcard.
Why do businesses want to verify their listings? In order to be able to protect their listings from fraud, manage information in search, maps and other Google properties, and attract more potential customers from search. Another reason is that if you don’t have a verified listing, somebody can try to verify it instead.
If your business is trusted by Google, it means that the search engine knows where your business is located, who’s the business owner and that your business does in fact exist.