Kirchoff‟s law of junctions(first law), Kirchoff‟s law of meshes(second law) are respectively based on

Kirchhoff's 1st law states that the total amount of current coming at a junction must be equal to the total amount of current going away from it i.e. the total charge must be conserved. Thus Kirchhoff's 1st law is based on the conservation of charge.
Kirchhoff's 2nd law states that the sum of the potential drop across all the components in a loop must be zero. Thus Kirchhoff's 2nd law is based on the conservation of energy.