You know how to read.  You don't have trouble with everyday reading tasks.  But in some classes at school, you're being asked to push yourself, and you find yourself working hard at some of the assignments.  You might struggle with getting all of the assigned reading done, since there's so much of it. Or you might not be able to determine what is relevant or important in what you are reading. Sometimes you are unable to grasp the key concepts, and so you feel like you are wasting your time. Recalling information that you read for a test or paper may seem difficult at times.

These are the types of problems that many students deal with as they try to take their education to the higher level in high school and college.  These are new challenges different from the ones you faced when you were younger and reading at a more basic level, and you need to learn new strategies to meet them.