What is the meaning of Quantity?

A fundamental, generic term used when referring to the measurement (count, amount) of a scalar, vector, number of items or to some other way of denominating the value of a collection or group of items.

An indefinite amount of something.

A specific measured amount.

A considerable measure or amount.

Property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as number and a reference.

Indicates that the entire preceding expression is henceforth considered a single object.

Length of sounds.

Source: wiktionary.org