Huissier translates to "bailiff", an officer who seizes property for unpaid debts. It's a specific and dramatic word you definitely wouldn't expect to find in a world-famous dance track.
In the song, Stromae lists a chain reaction of life's problems, singing "Qui dit dette te dit huissier" (Who says debt says bailiff). This sharp contrast between the harsh reality of the verses and the euphoric escape of the chorus ("Alors on danse" / So we dance) is what makes the song so brilliant and powerful.
This is one of the biggest dance hits of the 2010s, but listen closely to the lyrics. Stromae isn't singing about a fun night out. Instead, he lists all the problems of modern life in a big, depressing chain reaction. He starts with school: "Qui dit étude dit travail" (Whoever says study says work), which leads to money, which leads to spending and debt. He does the same for love: "Qui dit amour dit les gosses / Dit toujours et dit divorce" (Whoever says love says kids / Says forever and says divorce). It's a bleak view of the world where every step forward just leads to another problem.
So what's the solution when you're overwhelmed? "Alors on sort pour oublier tous les problèmes" (So we go out to forget all the problems). The answer is simple: "Alors on danse" (So we dance). The song suggests that when things get so bad that "pire que ça ce serait la mort" (worse than this would be death), and the problems just keep coming, the only thing left to do is dance through the misery. It's a party song for people who have nothing left to celebrate.