This gives a blaze 20 health points (because 1 heart = 2 health points). To kill a blaze, you need to inflict 20 points of damage to the blaze.
A fire is a blaze. Fire, when it's going strong and burning bright, is blazing. The greater the blaze, the harder a fire is to put out. You can also use this word for other types of brightness or shining.
