Greetings everyone I am Hadi.
As you know about SEO ( optimization ) and SEOer ( Optimizer). Now i am going to tell you what is relationship between between it.
SEO is a skill and SEOer learn it. If you take a complete course of SEO from anywhere. Should you call yourself SEO expert? From my point of single course is not enough, take several courses , you will get some thing new. For getting have taken courses of several hours. You need to read book,blogs, community answers and a lot more. This is not easy to complete yourself in this field. One thing always keep in mind do practical work more the watching videos.