The ozone hole came up as I started to answer a question about global warming. Clearly these are two subjects which get mixed up a lot, so I decided to talk about the ozone hole first. The ozone layer is near the top of the atmosphere, far above the troposphere, where all weather phnomena occur.
Ozone absorbs UV radiation from the sun, thereby protecting plants, animals and people.
Ozone gets destroyed by certain chemicals, most imortantly CFC's. CFC's are mostly used in refrigerators, airconditioners and spraycans. They were used there because they were very non-reactive and stable. Unfortunately they are so stable that they can survive for decades as they slowly diffuse throughout the atmosphere all the way up to the ozone layer. There they react with the ozone, if the temperatures are very low.