Search engine optimization or SEO is the process of optimizing a website to get unpaid traffic, known also as natural or organic traffic. This increse in traffic can be achieved by ranking higher in the search engine results page (SERP). SEO considers for example what targeted audiences search for - the actual search terms. It also considers algorithms that decide what search results will be displayed in a search.
Local SEO focuses on optimizing a website so that it will be displayed when users enter local searches for products or services. SEO does not focus on direct traffic or paid advertising.
Resources:
https://www.coursera.org/specializations/seo