Dreams of trying to fly often symbolize a desire for freedom or escape from limitations in your waking life. The fact that you can't reach above the terrace of your high school may suggest feelings of being stuck or constrained by past experiences, responsibilities, or the expectations of others.
High school can represent a time of growth, learning, and social pressure, so this dream might indicate that you are grappling with unresolved issues from that period or feeling held back by your current circumstances.
Consider reflecting on areas in your life where you feel restricted. Are there ambitions or goals you want to pursue but feel unable to? This dream could be encouraging you to confront those barriers and seek ways to overcome them, allowing you to achieve a sense of elevation and freedom.