This shows you coping well with what life is confronting you with, and having adaptability or mental quickness.
If it is someone else who is agile it might still refer to you, as your dreams often use other people to illustrate some of your own strengths and weaknesses. See: movement; postures movement and body language.
Agility in your dreams can mean that you are mastering the ability to use all the movements, postures, gymnastics of dreams. In other words you can change from being in a body or out of it, you can meet and deal with images of fear and anger; you can fly into the awareness of greatness and genius, you have become a master in the realms of death. See: movement; postures movement and body language.
Useful Questions and Hints:
Is the agility accomplishing anything, and if so what does that suggest in my waking life?
What does the dream suggest I need to be agile in connection with?
Does this in any way show me needing to be more flexible about something – work – a relationship?
Depending on what you are doing it might help if you use to explore your dream.