Roughly translated it means "not true" and can be used as that.
But most often it is used as a filler/comfirming word like the English "right" both in the middle and in the end of sentences, and can also be shortened to just "sant", "true".
So combined with the typically Nordic inward breathing "jah" you have half of a normal Norwegian conversation right there.
Like, I think I say "like" quite a bit. And I've noticed that I use "awesome" quite a lot. And "personally" when I'm giving my opinion about something, especially typing on a platform like this, I sometimes need to reword my shit to avoid frequent use of "personally" lol. Also, for some reason this stuck in my mind, according to a word cloud on Reddit a while ago, one of my most frequently used words of all is "people".
Other than that, I say "what the fuck" to myself fairly often while reading the news these days. And I think "holy shit" is also up there "awesome" for me.
Edit: oh I think I also say something like "know what I mean?" quite a lot too.