If you dream of being unprepared for something, it represents your fear of messing something up and failing. You may be worried and insecure that you don't have what it takes to accomplish a particular task coming your way.
Being unprepared, such as for a test or other situation, can represent:
A feeling or fear of being unprepared or unready for something
Recognizing the importance of whatever you were unprepared for in the dream, perhaps as a reminder to be sure and prepare for it
Feeling caught off-guard or "thrown for a loop" somehow in real life