from my understanding the /5 refers to the station. so -5 -4 -3 -2 -1 are stations towards the pelvis, when engaged it is a 0 and then on the way out of the birth canal it goes 1 2 3 4 and 5 is fully out. so i presume that 2/5 would mean she is at station -2 which is almost fully engaged and ready to come out fully. i dont know if that makes sense.