Question

why is it difficult to walk on a slippery road

Answer 1

We are able to walk due to force of friction between our feet and road .
But if there is any slippy medium between them than the friction reduce and chances of falling increases and we not able to even walk properly .

Answer 2

Explanation:

On the slippery ground, the friction is much less and we cannot exert a backward action force on it which would produce a forward reaction force on us. Hence, it becomes difficult to walk on a slippery road.