The space occupied by a substance (solid, liquid or gas) is called it's volume.

It's SI unit is cubic metre and is represented by m^{​​​​​​3}.

The mass per unit volume of a substance is called it's density.

It's SI unit is kg/m^{​​​​​​3}​​​​​ or kg m^{​​​​​​-3}.

The amount of surface occupied by an object or a place is called it's area.

It's SI unit is square metre and is represented by m².

The rate of change of motion is called speed.

It can be found by dividing the distance covered by the time taken in which the distance is covered.