An S video cable looks as pictured. This particular cable is 6 feet in length, but they can be longer.
What Does the S-Video Cable Do?
The cable connects to a television and carries a video signal from whichever output device you wish to use, separating the colour and black & while signals to achieve a sharper picture image. Such cables usually have a a maximum resolution of 576i. This means it cannot carry High Definition TV and so is likely to be phased out over the next few years, as more people switch over to HD.
This short film also explains the function of a S-video cable rather well:
