Question

Its difficult to balance our body when we accidentally step on a peel of banana

Answer 1

Assume a normal scenario with no banana peel.

When we walk our foot pressurises the ground in downward direction and to counteract that force, ground also pushes our foot in upward direction (with same force) and with the help of initial angle between our foot and ground, our foot tries to push back ground in backward direction and hence we're able to walk. (As the counteracting force from the ground will try to push forward our foot.)

Now there are many firm points of contacts between our foot and ground when we step on it (obviously!).

Force gets transferred to ground and back to our foot through these points of contacts only.

Now assume you accedently step on banana peel.

There would be no firm points of contacts between your foot and ground (as banana is not firmly adhered to ground) and hence our foot will pressurize the ground but there won't be any counteracting force from ground (due to absence of firm points of contacts)

Your foot will try to push back ground in backward direction but ground won't push forward your foot and hence you would loss balance.