Question

why is it difficult to balance our body when we accidently step on a peel of banana

Answer 1

because it has less friction which made it slippery

Answer 2

actually, when we accidentally step on a banana peel the difference in coefficient of friction between our feet and the ground decreases drastically due to smooth surface of banana peel. Thus we are not able to balance such drastic change in the value of friction and it becomes difficult to maintain balance.