Nikki Haley said that she would resign from her position as United States ambassador to the United Nations at the end of this year. She announced this in October. It should not seem unusual that she resigned since it was stated that it is a very difficult job that no one seems to want. She had to take charge and be in charge of the United Nations meeting during her first year in that position.
No one is sure what she will do next except probably right now she is relaxing. It is too early to tell what she will do next. Some speculate that she resigned because she will plan to campaign for the 2020 election, but she has denied that and has actually made jokes about it.