Withholding of removal is an order given by an immigration judge to a person who will be persecuted if they are deported to their home country. Their persecution may be because of their religion, nationality, social group, race, or politics.
The order prevents you from being deported to your country of origin. Withholding of removal will also allow you to work towards getting employment authorization if you so choose.
You must prove that it is more likely than not that you will be persecuted in your home country if sent back.
It is not discretionary like other rulings such as applying for asylum. But you must provide the proper proof. If you cannot prove that you would be persecuted, you will be required to leave the United States.