This course is about setting or worldbuilding. It mostly applies to fantasy and science-fiction, as those are the genres in which you actually design a whole new world. It has a healthy chunk devoted to magic systems as well.
It, however, also contains more general tips (at the start). These help pick the most interesting and rich setting possible for whatever story you want to tell.
Setting is one of the three pillars of story, next to character and plot. Although usually put in the third place (behind character first, then plot), it’s still a crucial aspect to get right.