According to the Merriam-Webster Dictionary, metaethics is "the study of the meanings of ethical terms, the nature of ethical judgments, and the types of ethical arguments." To better answer the question posed above, it is useful to compare ethical subjectivism with ethical objectivism.
According to ethical subjectivism, objective moral truth does not exist. The truth or falsehood of moral statements is dependent upon attitudes or perceptions. Morality has no absolute or universal basis; instead, it changes according to time periods, geographical locations, cultures, and each individual's unique perspective.
One of the difficulties with ethical subjectivism is that morality is based not upon what is good or bad but rather upon how people feel about something. So, for example, if someone wanted to justify murder, they would not have to prove that murder is warranted but only prove that they feel or believe that murder is justifiable action. Taken to an extreme, ethical subjectivism would absolve the perpetrators of genocide from blame if they felt that what they were doing was right.
In ethical subjectivism, it is inherently impossible to dispute a moral fact because morality is subject to the opinions of each person debating the issues. Disagreements cannot be resolved because no absolutes exist by which to compare them. Those who disagree with each other have no choice but to acknowledge and tolerate the viewpoints of others.
On the other hand, according to ethical objectivism, moral values are fixed truths that do not change. They apply equally to all regardless of time periods, geographical locations, cultures, and so on. In ethical objectivism, if two people disagree with each other on moral grounds, only one of them can be right. In moral considerations, all people are equal.
An extreme form of ethical objectivism is moral absolutism, which regards certain actions as always wrong regardless of circumstances. Considering murder as inherently wrong would be one example. Religious principles such as the Ten Commandments are based upon moral absolutism.
Whether anyone is ultimately correct in their moral judgments or absolute right and wrong exists are questions that you should answer according to your personal opinion. Use these basic definitions and examples of ethical subjectivity and objectivity as guidelines.