The Fundamental Quantity is independent Physical Quantity that is not possible to express in other Physical Quanitity. It is used as pillars for other quantities aka Derived Quantities. In Physics, Length, Mass, Time, Electric Current, Thermodynamic Temperature, etc are examples of Fundamental Quantities.
Area =m2 Volume =m3 Force =kgm/s2 Pressure =kg/(ms2) Density =kg/m3" The seven fundamental S.I units are:− metre → for length second → for time kilogram → for mass kelvin → for temperature ampere → for electric current candela → for luminous intensity mole → for the amount of substance.
Identification of fundamental quantities
A fundamental unit is a unit adopted for measurement of a base quantity. A base quantity is one of a conventionally chosen subset of physical quantities, where no subset quantity can be expressed in terms of the others.