Principle of Homogeneity of dimensions

This principle states that

In a dimensionaly correct physical relation the dimension of each and every term on both sides of relation must be same.

 That is according to this principle;

1 We can add or subtract only those physical quantities which has same nature ( mean if they have same dimensions).

2 A physical relation must be dimensionaly homogeneous i.e. all the term on both sides of the relation must have the same dimensions.