They're basically just meant as definitions referring to either "side" of a political spectrum as defined by looking at the fiscal and social ideals of the given parties, grading them on a scale of difference with each other, and then aggregating that into a kind of general position on the spectrum. "Left", at least in the case of the US and Norway, tends to refer to more of a liberal position of socialized services, while "Right" tends to refer to a more conservative position of privatized services. That's a massive oversimplification, but digging into the meat of "liberal" vs. "conservative" is... Tricky. Especially when trying to maintain some degree of neutrality in it.
Places like the US tend to view left-right as a... Well, a binary spectrum. It's just a different way of writing "us versus them". Blues against Reds.
Norway is a bit more nuanced, which also often leads to hilarity. With the "Right" party being right of center, the "Left" party officially being left of center but frequently allying with the Right party in order to gain traction, the "Center" party honestly being kinda right-ish too but simply not caring about external affairs enough to be classed effectively, the "Progressive" party being farther right than Right (to the point where they ended up bailing out of the last conservative coalition, because they didn't like how left Right was being, so they left), and the Christian People's Party (not to be confused with the People's Party of Christians. No, really) being split between the leftist views of the members following the teachings of Christ and the rightist views of the Christian members.
Also red/blue have opposite definitions compared to the US, and there's also green and yellow (plus orange, but nobody actually gives a shit about orange)