Purpose relates to having a clear idea of the goals you want to achieve.
You can have multiple goals covering various areas of your life - academic, personal and social - and you may have a stronger sense of your goals in different aspects of your life. For example, you may have a strong sense of your academic goals but a less steady idea of your personal and social goals.
Having a goal-oriented outlook
Watch this video for a brief introduction to the importance of focusing on goals in the various aspects of your life.