This option is only available in tactics courses. If you change this option it will apply to the particular tactics course you've set it for. The default option is set to 'Solve Problem'.
Solve Problem: You will need to solve the exercise yourself and MoveTrainer™ will not teach you the moves.
Show Solution: MoveTrainer™ will show you the moves to make and you repeat the moves. It works the same as how you learn an opening course.