SEO is super sexy, in-depth and can be pretty complex.
The best thing you can do, what I´d recommend you to do at
first is to check out some free content such as blog posts, so that
you can receive some basic information.
SEO is all about optimizing your content that would be blog post, articles,
pages and more so that the search engines such as Google want to rank you
higher than your competitors.
Now it comes, many people think they know SEO, but in reality have very
little till zero knowledge about it.
Hope this helps!