Most digital cameras have "3× optical zoom," which is really only adequate if you never need to take shots from a long range. Having "10× optical zoom" means being able to get that close-up shot from the back of the room, without getting out of your seat to block other people's view. Or get a good look at something you can barely make out with your naked eye.
So here, an example of the zoom in use from pictures I snapped at Taipei 101:
This was taken without using any zoom.
The zoom in this photo is around 3.4×, which is slightly higher than what most digital cameras are capable of.
At 10× zoom. Also note that these pictures were sized down for Blogger, so the original, 7.2 megapixel picture is almost twice the size of the 1600×1200 images you see here (and about 8 time larger than the thumbnail images in this post).