Which layer of atmosphere protects life on Earth from harmful radiations coming from the Sun & space?

Answer: Ozone layer

The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is potentially damaging to the life forms on Earth. It is mainly located in the lower portion of the stratosphere from approximately 30 to 40 kilometers (19 to 25 mi) above Earth, though the thickness varies seasonally and geographically. The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. In the 1970s scientists discovered that certain man-made chemicals deplete the ozone layer leading to an increased level of UV radiation overhead, is named in his honor. The ozone layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun.
While stratospheric ozone, which protects us from the sun, is good, there is also ozone produced near the ground, from sunlight interacting with atmospheric pollution in cities that is bad. It causes breathing problems for some people, and usually occurs in the summertime when the pollution over a city builds up during stagnant air conditions associated with high pressure areas.