SEO is imaginatively linked to marketing for content that you want to rank organically (which is not content at all). You want to know what topics your content is trying to show in Google. The most important thing here is that you satisfy the search purpose of the topic (s) you are trying to show. There are many basic things (related to HTML tags, etc.) that you want to follow, as well as some noise (e.g. internal connection, UX, empathy) that you need to pay attention to.