ISF / Overrunning 1st Base

[mach3]

ISF-Rules.

Rule 8
Section 9 The Runner is out
[…]
i. When the batter-runner becomes a runner by touching first base, passes it, then attempts to run to second base
and is legally touched with the ball in the hand(s) of a fielder, while off base.
[…]
EFFECT - Sec. 9g-j:
These are appeal plays and the runner will not be out unless the appeal is made legally.
1. Appeals may be made while the ball is alive or dead, but the defensive team loses the privilege of making an
appeal if it is not made

My questions are:
Why is this an appeal play? What do we expect the players to do?
What consequences does that have?

Thanks for your help.

Raoul