Wear sunscreen and do not spend huge amounts of time in the sun.
We have a gaping hole in our ozone layer and this makes the sun legitimately lethal. If you remain in the sun for an extended period of time, even during winter, you have a very real chance of severe sunburn. You can suffer from heatstroke. Your sunburn will blister. You can get third degree burns.
You can go to the beach and enjoy yourself but don't fall asleep in direct sun for a couple of hours at noon or you might just get a ride to hospital.