What does it mean "Remaining watch time until is unlocked is :30 min"? Can I take the exam again?

Hi A M MOSTAHSIN, Thanks for reaching out! In order to retake your course exam, you need to go back to this course and complete at least 30 minutes of video lectures before your exam is unlocked again! You can do this by going to the "Courses" page and rewatch the video lectures for this course under the "Completed Courses". Hope this helps! Kind Regards, The 365 Team