A frame rate is the the speed at which the browser is able to recalculate, layout and paint content to the display. The frames per second, or fps, is how many frames can be repainted in one second. The goal frame rate for in web site computer graphics is 60fps.
Movies generally have a frame rate of 24 fps. They are able to have fewer frames per second because the illusion of life is created with motion blurs. When moving on a computer screen there are no motion blurs (unless you are animating an image sprite with motion blurs).