Some global issues have prompted partnerships between seemingly strange bedfellows at opposite ends of the political spectrum. The ‘horseshoe theory’ tries to make sense of this, but what’s it about?
Horseshoe Theory believers tend to be fond of libertarian-authoritarian axis erasure, so they think the opposite of fascism is Stalinism instead.
And yeah, auth-right dictatorships and auth-left dictatorships are indeed pretty damn similar, so they'd have a point... if their premise weren't unfounded to begin with.
Ultimately, a single axis system is completely inadequate to describe anyone's political position.
But for a single left/right, left is communism/socialism/"state capitalism", right is unfettered capitalism. In the "middle" is regulated capitalism with some welfare.