Google Business Profile (formerly Google My Business) is the free listing that appears in Google Search and Maps for local searches, showing your business name, location, hours, reviews, photos, and more. Optimization means filling out and actively maintaining every relevant field — categories, services, business description, photos, posts, and Q&A — to both rank well and genuinely help the person viewing it decide to contact you.
Ranking-wise, Google weighs how complete, active, and accurate your profile is. Beyond ranking, a well-optimized profile directly affects conversion: it's frequently the deciding factor between two similarly-ranked businesses.