Eyebrows are a very odd feature which many people have. Some don't, but the majority of us do. They are little lines of hair above your eyes. Their main purpose in life seems to be that they can wiggle up and down. They are also good for making strange and insane faces so that nobody will come near you while you are buying something you don't want to be seen buying 1. Of course, this sometimes has the opposite effect - people sometimes look at you instead of away from you, but this is just a minor drawback.
Scientists reckon that eyebrows are there so that rain and sweat don't drip into your eyes. I reckon that you shouldn't be doing anything that requires so much effort that sweat might be dripping into your eyes. And if it's raining, what do you think cars are for? Another thing about eyebrows is that many people enjoy the excruciating torture of tweezing them out, hair by hair, so that they look like plucked chickens. Honestly.