Complement code with a class

Hello, I have this class called CostPersonal, and I have to create a treballador class that complements it but I do not understand when it refers to treballador.DIRECTOR

public class CostPersonal {

    static float CalculaCostDelPersonal(Treballador treballadors[]) {
        float costFinal = 0;
        Treballador treballador;

        for (int i = 0; i < treballadors.length; i++) {
            treballador = treballadors[i];

            if (treballador.getTipusTreballador() == Treballador.DIRECTOR ||
            treballador.getTipusTreballador() == Treballador.SUBDIRECTOR) {
                costFinal = costFinal + treballador.getNomina();
            } else {
                costFinal = costFinal + treballador.getNomina() +
                    (treballador.getHoresExtres() * 20);
            }
        }
        return costFinal;
    }