Search Engine Optimization is an annoying buzzword.
A search engine – is a program that searches a database of information to find a result. The only people optimizing those – are the people who are paid to build, maintain, and improve them. In many cases – they improve themselves based on your search queries.
SEO is what people think of as optimizing your website so that search engines will pay more attention to it.
Luckily – you are learning how to write proper HTML, so that will happen from the get-go.