The camparison of any physical quantity with its standard unit is called measurment.
All the quantities which can be measured directly or indirectly in terms of which the law of physics are described called physical quantities.
A standard amount of a physical quantity chosen to measure the physical quantity of the same kind is called physical unit. It should be easily reproducible, internationaly accepted.
Fundamental Quantities and Their Units:
Those physical quantities which are independent to each other are called fundamental quantities and their units are called fundamental units.