I have a website on shopify and am trying to learn about SEO and getting optimum results out of it. I've been doing a lot of reading but the concept still seems to be eluding me for the most part. Are there any tips or tricks or can anyone summarize what i really need to do...in English?

Also, is there anything special to know about using Google AdWords?

AdWords is a paid service, you can use Semrush instead, it has a limit - 5 keywords a day but usually it is enough. About seo, just make sure you have quality and unique content and you somehow leave traces about you in the Internet.

SEO is all about Ranking your site for specific keywords in the Search Engines. You need to have your main keywords in the title and used throughout the article. The content needs to be readable and engaging and gives value to the reader. This will help keep the visitor on your site lowering bounce rate. They may also share your content which will give signals to the search engines that your webpage is valuable.
Backlinks are required as they act like votes. More backlinks means more votes but they must be acquired naturally. Also some of the backlinks need to have your keywords in them.