Here are some examples:
* 이 세상: This world
* 세상 사람들: People of the world
* 세상이 다 아는 사실: A fact known to everyone in the world
* 세상은 넓고 할 일은 많다: The world is wide and there is much to do
It can also be used in more abstract contexts to refer to:
* "reality": The way things are
* "life": The experience of being alive
* "existence": The state of being
The specific meaning of "sesang" depends on the context.