Google Maps SEO is the practice of optimizing your online presence specifically to improve ranking in Google's local map pack results — the map and top three business listings shown for local search queries.
Google evaluates map pack rankings using a combination of proximity (how close your business is to the searcher or the searched location), relevance (how well your profile and business match the search query), and prominence (how well-known and trusted your business is, based on reviews, citations, and overall web presence). Improving your position means strengthening all three, not just one in isolation.