Hi Shakis,
Glad you're liking this :) Those variables are what make the branching work, since the first part of the course is the same for both types of learners.
If you had a course where the content was completely separate, you wouldn't need those variables, you could just set up the triggers to lead to those slides directly.
But because the first part of the course is the same, and I didn't want to duplicate it (which would create extra work for me if I ever needed to update the course) I used these variables so that Storyline would "remember" which button the learner clicked when they get to the part of the course where the content is different for the different type of learner.
Does that make sense? Let me know if not! :)