UV radiation (aka ultraviolet radiation) is a form of radiation, usually emitted by stars.
Protection from UV radiation comes from atmospheric protection, in terms of an ozone layer. Planets such as Avnil are greatly effected by UV radiation due to minimal atmospheric protection, this creates hazardous conditions for outdoor traveling and minimal life. Two solar radiation shields can create a force field that blocks UV radiation much like an ozone layer. (SG1: "The First Commandment")
Other types of protection from UV radiation can come from radiation suits and sunblock. (SGA: "Runner")
The UV index of P3M-736 is like a thousand during the day, but somehow the planet's plant life continued to thrive despite what should be extremely destructive ionizing radiation. (SGA: "Runner")