What do you mean by 320x480 pixels?
320 x 480 pixels typically would mean that the display of the
technological device, (probably a television, computer monitor, or
other visual device. etc.) would have 320 pixels on the shortest
side of the screen and 480 pixels on the adjacent side. Thus the
screen would have 153600 total pixels in the screen, but by writing
the dimensions, the manufacturer can keep better track of the
brands and not be faced with two different dimensions equalling the
same number of total pixels.