The sunburn timer helps them to calculate the time you can spend in the sun without harm. The timer reminds you when you should put some cream again. The calculations are based on scientifically recognized and tables are pretty close to the real value.
After the start adjust skin type, sun intensity and the Sun Protection Factor of your sun creme.
Start the timer if you want the alarm function to.
Under "TREAT SUNBURN" You find additionally a contingency plan if you should get a sunburn.
Under "SUNBURN" are still to information where you can learn all there is about sunburn, so that no more questions should be open.