Google (and other search engines) crawls the internet with bots that gather information about webpages and place them in an index.
Powerful algorithms analyze these webpages in the database, comparing hundreds of variables or signals, to decide which order websites or other digital properties (such as social media channels, Google Maps
listings, and more) should appear for any given search query.
A professional SEO company adjusts key factors that influence the signals Google is reading and making decisions upon. One such factor is the topical relevance of your content: how cohesive, thorough, and coherent is it, and how does it pertain to the key terms for which you're trying to rank?
Another factor is brand prominence. Another is trustworthiness. There are many more as well. A good SEO company understands these ranking factors and has specific processes and techniques that improve the signals your business is sending.