Normally, you can do the next question you must pass the current question. So you can complete one section you must correct all questions in the section.
75% Pass Mark has the process from user attempts to answer the question. Because of this course, you will never get failed question. You had to retry to answer the question until you got the correct answer then you can go to do the next question.
75%% Pass Mark is the percentage that you must pass in all questions. Then 25% is the percentage that you can attempt to fail the question.
So, currently, the course has 27 questions. It is mean when you had attempted to answer the question and you got an incorrect answer 7 times (25% of 27 is 7). You failed the course.