Eldorado refers to the mythical city of gold, a place of immense wealth and opportunity. It's a word that evokes dreams and aspirations.
In the context of the song, it's used to represent the protagonist's shattered American dream. The line "Fini l'eldorado" (The eldorado is over) powerfully conveys the end of her illusions and the harsh reality she faces in Hollywood, making it a poignant and memorable choice.
M. Pokora tells the story of a young woman chasing the American dream all the way to Los Angeles. She has "Hollywood Boulevard dans la peau" (Hollywood Boulevard in her skin), she "rêve d'une Cadillac" (dreams of a Cadillac), and she goes "de casting en casting" (from casting to casting) hoping to "faire la une de tous les journaux" (make the front page of every newspaper). The chorus keeps returning to the postcard image: "Elle rêve de Santa Monica, California Sunset" (She dreams of Santa Monica, California Sunset).
The details turn dark fast. She drowns her pain "en deux-trois-quatre shots" (in two-three-four shots), swallows "deux-trois pills" in strip clubs, and leans on "Xanax, Lexomil" while the song asks "verra-t-elle la fin du film?" (will she see the end of the film?). By the last verse it is "Ambulance, Hélico" and "Elle s'endort en sanglots" (She falls asleep sobbing), and the chorus slips into the past tense: "Elle rêvait" (She dreamed). Listen for that switch from rêve to rêvait, it is a neat way to hear the French imperfect tense doing real storytelling work.