Wikipdia Summary: The series takes place after the events of the film Avengers: Endgame (2019), in which an alternate version of Loki created a new timeline.
What do you make when a villain actually gets popular and the person in the part is actually liked? You turn it into a hero!
Sure, it worked wonders for Catwoman.
But yeah, this time is Loki.
For the action of taking the tesseract in "Endgame", Loki is now under arrest by some time agency, which you never heard before, for "breaking the timeline". Of course, the Avengers, when they broke the timeline, it was expected, so they are Ok, but Loki is not. So, what happens? The agency hires Loki to take the other representations of Loki, so now Loki is in to save the universe.
So, while "Falcon and the Winter Soldier" tracked the problem with the way USA deals with black people (including black soldiers) and "Wandavision" tracked the problem of dealing with loss, "Loki" deals with... the idea of turning a villain into a hero for money.
Not that Tom Hiddleston let his acting down, or even Owen Wilson, but the fact that the series was created purely to take on the popularity of Hiddleston character is a major let down.