Watch out for zoom figures like "100x" or "600x". That is just baffling the buyer with bull manure.
The actual optical length of a lens is measured in mm. Although that can be confusing for non-professional photographers. For non-pros, just remember that you need to actually, physically see what the lens can do before buying it.
The technical: For a 35mm film or DSLR camera, a normal perspective lens is around 50mm. Multiply that by 6x and you would have a 50-300mm zoom lens. That's a pretty good zoom. Multiply by 12x and you have a 50-600mm lens. That's a really long lens - most people would need a tripod to get any non-blurry photo out of it!!
And that's only so-called "12x". But misleadingly larger numbers sell things, so -
Start with a really wide focal length, like 18mm. Lots of distortion, low quality, it doesn't matter if all you're trying to do is sell a camera.
Now multiply 18mm by 12x, and you have an 18-216mm lens. Much cheaper to make, and the bigger "12x" number makes it sell better.
Now make the size of the sensor smaller, but give it more mega pixels ( = lower quality), and the numbers get bigger on paper....
And on and on it goes.
One of my mentors said "The best zoom lens is your legs."
Within certain bounds, he was right.
The image below was taken with an old DSLR, using a wide aperture and a clever angle to blur the background, and my legs were the zoom, along with some patience. This photo was not taken with a 'superzoom', or a fancy camera with a big "4,000x" zoom. I think it was about 180mm in 35mm terms.