Here is a link to an article about it,

https://www.semrush.com/blog/what-is-seo/?kw=&cmp=UK_SRCH_DSA_Blog_Core_BU_EN&label=dsa_pagefeed&Network=g&Device=c&utm_content=484278208025&kwid=dsa-1053501802787&cmpid=11776881484&agpid=113846074545&BU=Core&extid=167346300070&adpos=&gclid=Cj0KCQjw8vqGBhC_ARIsADMSd1B3A0x1xch_25Od-akjAfa5oV7J4YYjMQJSgyaaeFC8uTW5NnORRoQaAkRBEALw_wcB

Basically it is how your website is referenced by search engines like google. If you do not get this right when people are searching for you will not appear in the results and as such you will never get listed.

Companies such as the link above of course will do all this for you…..but at a cost. However a lot of the website hosts / builders, such as wordpress, wix, etc will have tools built in to allow you to fix this yourself.

A great FREE tool to check how your site works with SEO is:

https://www.seobility.net/en/seocheck/

Enter your website address and click Analyse Website

The next link is an example of one of my website pages:

https://freetools.seobility.net/en/seocheck/check?url=https%3A%2F%2Fraidogebodagaz.com%2Fevents%2Ffantasy-forest&crawltype=1

As you can see it is green meaning it is ok. 82% is not the best score but it isn’t a bad score.
You can read down and it gives advice about what works and what doesn’t.
My issue is about too many files, unfortunately this is out of my control as I use WordPress and this is just how it works.
The two key bits is to ensure you have a decent heading that has the right code (H1) and you have a meta description. This is usually a small part from the text of your website or something you enter specifically for search engines explaining what the page it.

Without decent SEO on your website you will never get listed on search engines.