SEMRush is known for their authority on SEO and all SEO related tools and topics. They are very well known and know what they are talking about in this free course.
Covering topics like crawling your website and HTTPS issues, you should know some SEO stuff before trying to use the tools provided here. If you are wanting to learn how to optimize an already existing website and to fix problems, then this is a valuable resource. You can also get a certificate at the end, which looks professional when talking to customers!