I have a N70 mobile phone.Around the lens of the back camera these numbers can be seen: 4.8mm 1:3.2?

what do these numbers mean?what do they show?

The focal length of the lens is 4.8 mm. It's a wide angle lens, probably near a 24 - 36 mm focal length equivalent compared to a 35 mm camera.

The aperture (the opening which lets light in) is f/3.2. You will be able to take photos in moderately dim light, but not in really dark places. For comparison, the white Canon lenses you see at sports events are often f/2.8.