Although the details of the meeting between Kim Jong Un and Chinese leaders are largely unknown, it is thought that Kim meant with Chinese leader Xi to patch up some of the rough patches that have happened between them, mainly because of Kim Jong Un's lack of consideration. It is also thought that the meeting was stemmed from the fact that North Korea is considering some economic growth reform which would benefit a good deal from China.
It could also mean that Kim Jong Un is attempting to lead South Korea out of the protection of the United States under the false hope they'd be okay and there would be no attacks. It is all speculation at this point, though.
