@omi-kun
SEO stands for "Search Engine Optimization" It means the process of making your site better for search engines. It aims to improve your website's position, traffic, ranking in search results pages.

There are two equally important parts: on-page SEO and off-page SEO.

On-page SEO is about building content to improve your website ranking, optimized HTML source code as opposed to off-page SEO which refers to links and other external signals.
Off-page SEO refers to all the things you can do outside of your website to help you improve SERP position: link building, forums, influencer outreach, content marketing, etc.