Normative ethics (cf. metaethics) is the branch of the philosophical study of ethics concerned with classifying actions as right and wrong without bias, as opposed to descriptive ethics. Normative ethics regards ethics as a set of norms related to actions.
Descriptive ethics deal with what the population believes to be right and wrong, while normative ethics deal with what the population should believe to be right and wrong.
"Killing one's parents is wrong," is a normative ethical claim. Given that parricide is wrong, normative ethics has no further interest: why it is wrong is someone else's concern.
Moreover, because it examines standards for the rightness and wrongness of actions, normative ethics is distinct from metaethics, which studies the nature of moral statements, and from applied ethics, which places normative rules in practical contexts.