The prefix 'Hexa' is derived from the Greek word for six, and is used to denote a quantity of six. It is commonly used in mathematics, chemistry, and other sciences to refer to a group of six elements or objects. For example, a hexagon is a shape with six sides, and a hexadecimal number system is a base-16 number system that uses sixteen symbols to represent numbers. Hexa is also used in computing to refer to a group of six bits, which are the smallest unit of digital information.