What is the difference between a vector and a scalar quantity?

A vector describes both magnitude and direction, whereas a scalar only describes the magnitude. A common example is speed and velocity. Speed is a scalar, it describes only how fast something is going and velocity also describes the direction in which it is going. Another example for a scalar quantity is temperature. Temperature obviously has a magnitude, but there is no direction, no change. Force, however, is a vector quantity. It isn't just important how big the force is, but also in which direction it is applied. Whether I push a ball to the right, or to the left makes a difference and this is the information that a vector carries when we say it describes direction - in addition to magnitude.