Use the adjective high to describe something with a great elevation. If you want to see a really high mountain, you should visit Mount Everest.
You can also use high to describe a sound or musical note that is elevated in pitch. Some stores use a high-pitched buzzing sound to keep teenagers from loitering. The noise drives teens crazy, but it doesn't bother their parents, because adults can't hear the high frequency. High also means a state of euphoria. After you win a first place medal at the swim meet, you might be on a high for days.