This is an instructive position from The Genesis of Power Chess by Leslie Ault. One of the many instructional positions on cashing in during the early endgame. There are actually two ways for White to win:
One of the ways is to sacrifice the Rook. The second method is to simply advance the Pawns.
A slight change in position changes things. If the Black Rook is moved to e7, only one of the methods will work. Also, if the White King is moved to g1, only one of the methods will work. This book has many similar fascinating instructive positions.
A interesting mini game, which may not have ever happened (Gibauld denies that he ever lost such a short game), shows how a careless move in the opening can be fatal.