How it works is that you're in control of a nation. Your nation will get issues every so often (once every couple of hours early on; but once or twice a day later). You decide what the right choice is based on the options given to you and you get some consequences based on that.
For most issues, there's no clear-cut right or wrong answer. Many of the options are designed to have both positive and negative effects. While some issues will have one answer that'll clearly be disastrous, the other two or three will usually be at least somewhat reasonable choices.
The issues are written to be humourous. The results are usually written to be that way, too.
While some other users have said the game is designed to frustrate conservatives, I don't think that's necessarily the case. Everyone understands that in the real world, whatever policy choices politicians make are going to have benefits and they're going to have drawbacks, regardless of which side of the political spectrum they're on.
It's the same with Nation States. If you think otherwise, you're probably not very good at nuanced thinking. You're probably also bad at knowing the difference between a fictional game (which Nation States absolutely is) and reality.
But generally, the game's pretty good. I'd definitely recommend it to people.