Diagram
1...Kf8
Black must begin by moving within the square of the pawn. Just imagine a square, in this case reaching from b4-b8-f8-f5. To prevent the b-pawn from queening, the black king must be able to stay within the shrinking square as the b-pawn advances.
2.Ke3
White knows that the king needes to move ahead of the passed pawn to clear its advance
2...Ke8
3.Kd3
Heading towards b5
3...Kd7
4.Kc4
Kc7
5.Kb5
Kb7
Diagram Black takes the opposition, blocking the further advance of the king.
6.f4
White will win quickly if the black pawns run out of safe moves. The king would then move to a5 and assist the advance of the b-pawn. So more accurate may be g5 immediately limiting the movement of the black f- and h-pawns. [6.g5
e6
7.f4
]
6...e6
7.g5
It sure works here!
7...Kc7
exd5 and e5 fail, but so does giving ground to the king
8.Ka6
exd5
9.Kb5
Kb7
10.Ka4
The point is simple. White will capture the d-pawns and wind up near black's kingside.
10...d4
11.Kb3
d5
12.Kc2
Kc6
13.Kd3
Kb5
14.Kxd4
Kxb4
15.Kxd5
Kb3
16.Ke5
With an easy win by capturing on f7. 1-0