“Radiation” is a catch-all term leftover from the late nineteenth century, before we knew much about physics. It is applied equally to various types of nuclear emissions and also to electromagnetic emissions, but these are not all the same.
Electromagnetic radiation includes a wide spectrum of wavelength, each with a different energy.
At one end of the spectrum are microwaves (harmless unless used in high enough intensity to heat you up) and radio (pretty much completely harmless). At the other end of the spectrum are X-rays and gamma rays, which contain enough energy per photon to break a chemical bond, and therefore potentially cause cancer or simply cell death. In the middle lies UV light, the shortest of which just barely has enough energy to influence chemical processes in living things enough to cause cell damage or cancer.
But, living things are not defenseless, and exposures are not magic death cooties. So while excessive exposure to UV light might cause sunburn and raise your cancer risk, you actually need a certain amount of exposure to maintain healthy vitamin-D and cholesterol levels, and an occasional x-ray is a valuable diagnostic tool.