y=2x-3 can be drawn as a graph. When x=0, y=-3, so -3 is the y intercept. (The x intercept is where y=0, and that would be where 2x-3=0, 2x=3 and x=3/2 or 1.5 or 1 1/2.) On a graph the y intercept is where the straight line cuts the y axis (and the x intercept is where it cuts the x axis).