Statistics is a branch of mathematics that allows you to draw conclusions about a large group of people based on information collected from a smaller group. It's also a tough college math course.
Say an Australian study reports that 45% of fifteen-year-old Australians like grape soda. The people who conducted that study didn't interview 45% of Australian fifteen-year-olds; they interviewed perhaps a fraction of the Australian fifteen-year-old population and based their conclusions about the entire population on that. This is the essence of statistics, and the uncertainty surrounding such studies is one reason why people who practice statistics have to take tough college courses.