Can someone explain part (b)?

[Robert E. Harrison]

8.3.1 SITUATION A: With R1, R2 and R3 on third, second and first bases,
respec tively, and (a) two outs or (b) one out, R1 attempts to steal home. With a
1-2 count, the pitch hits R1 while the ball is in the strike zone. RULING: In both
(a) and (b), ball becomes dead immediately and batter is out because of third
strike. In (a), no run is scored since batter became third out. In (b), all base runners
are awarded one base from where they were at time of pitch and R1 scores.
(5-1-1a, 6-1-4, 8-1-1 note 1, 9-1-1a)