Hello there!
First of all, we need to know the meaning of "Foreshadow"
Foreshadow is a warning. (Like when someone is talking to you they can warn you)
This is an example of the word "Foreshadowing"
I am foreshadowing you that you might fail your Chemistry class if you don't study enough.
As you can, this is like a warning or signal that something will happen.
FYI, I used that example because I am about to fail my Chemistry class :)
Anyway, I hope that answer helps and please let me know if there's something else I can help you with.
Thanks!