i dont understand how to graph the derivative of a graph.

i have an example of a graph in the book.
they show the points (-4,0) (0,2) (1,-2) (4,-2) (6,2)

it asks to graph the derivate, and for the values of x between X= -4 & x=6 where the function is not differentiable.

(can someone please explain what that means?)

Thank You In Advance