Phase:

A phase is a region of space essentially a thermodynamic system throughout which all physical properties of a material are essentially same.It is sometimes used as a synonym for state of matter. It is denoted by 'P'.

Component:

In thermodynamic chemistry, a component is a chemically-independent constituent of a system. The number of components represents the minimum number of independent species necessary to define the composition of all phases of the system.It is denoted by 'C'.

Degree of freedom:

The number of degrees of freedom is the number of independent intensive variables, i. e. the largest number of properties such as temperature or pressure that can be varied simultaneously and arbitrarily without affecting one another.

Now in a thermodynamic system, by Gibbs' Phase Rule,

$F = C - P + 2$ Here:

F : Degree of freedom

C : Component

P : Phase