We are given the function y= -4x and we want to find the value of y for some values of x.
We calculate
x=-2
x= -1
x=0
So we get the following table
x y
-2 8
-1 4
0 0
now, to plot this points, we draw a Cartesian plane. On the horizontal line (the x axis) we will locate the value of x and on the vertical line (the y axis) we locate the value of y. We plot each point and we get the following graph
so we join the points with a line to get the graph of the function. That is