It's when a light blood vessel in your eye bursts, so you wouldn't be cooked. It doesn't affect your vision or anything except making the white in your eyes (known as eye whites or the sclerae whites) have a red/bloody patch. It's only bad if you have it and the conjunctiva (the clear layer of your eyes) breaks, which means the blood will come out and your vision (and many other things) can be severely affected.
