Ultraviolet refers to wavelengths of light which are just a little bit outside the range which humans can perceive. It is not visible.
Some fluorescent materials can be lit with UV light, because they will fluoresce at wavelengths we can see. Otherwise, UV lamps also emit visible wavelengths.
This is a bit of a nitpick, but most people (especially children) can see at least a bit into UV. With my contacts in, I can see down to about 400-410nm. With them out, I can see to about 390nm, because the plastic in the contacts blocks shorter wavelengths. I tested this using a spectrophotometer.
People who have had cornea-replacement surgery and opted for the UV-transparent corneas can see further into the UV.[1] A child (with young corneas that haven't yellowed at all) almost certainly can too.
Slighly off topic, but UV visibility is important in other species. See this link for photos of flowers showing how they appear to bees or birds.
The CIE charts don’t really consider how to interpret or recolor data outside the color space, for example the UV reflection from flowers or astronomy photos in the UV/X-ray spectrum.
Some fluorescent materials can be lit with UV light, because they will fluoresce at wavelengths we can see. Otherwise, UV lamps also emit visible wavelengths.