Foreshadowing means having an indication of a future event. To foreshadow is to signify, or be warned of a future event.
RICHARD III (Duke of Gloucester): Go, tread the path that thou shalt ne'er return.
Simple, plain Clarence! I do love thee so,
That I will shortly send thy soul to heaven,
If heaven will take the present at our hands.
But who comes here? the new-deliver'd Hastings?
This text implies that Clarence will face death and that Richard will be the one to send him to die.