What is a 'aura'?help please?

My nan recently died and im 14. tonight my auntie(who's like a sister to me) went to a place to talk to a 'physic' lady to see if my nan was there. she wasnt but she said a little girl who my auntie used to pay ballet lessons for (me) was in her aura. so apparently im in her aura. whats that?