bracketing would involve shooting of 3 frames or more in different EV settings.
e.g. 3 frames of 1 stop difference
-1
as metered
+1
or 5 frames of 1/3 stop difference
-2/3
-1/3
as metered
+1/3
+2/+
this is meant for difficult situations which you want to come out with the best possible shot in that situation.