It means the context is giving you different clues or hints in order to understand the meaning, but it is not actually stated.
For instance, let's say you are talking to your friend, but he is not really looking at you in the eye, he is constantly yawning and he is also checking his watch. What is the implied meaning here? He is bored. However, he does not say anything, you just imply it out of his behavior.
Implied is something that is not directly indicated, but is suggested. When you eat a meal that you do not like and make a gesture of disgust, it is an example of a situation in which your disgust is implied, even if you do not say it.
It would be very difficult because there are a lot of people in my middle school. It would be the hardest in P.E in my opinion, because you can't hear or see if there is a ball being thrown at you. You can get hurt.