Can you check again as to what model of pentax you have? sn1 doesn't sound familiar. If we know which model it is, we may be better able to point to what you need to look for or expect to see.
The meter is built into most relatively modern 35mm cameras. It usually gives some sort of indication in the viewfinder and/or on an LCD screen on the camera as to which shutter speed and aperture the camera recommends when you point it at a subject. If set to "Auto" the camera may also set those settings for you, unless you choose to over-ride them.