Oseille is a French slang term for "money." While it literally means "sorrel" (a type of herb), it's commonly used in informal contexts to refer to cash or wealth.
In the song, Niska raps, "j'mange trop d'oseille pour être au régime," which translates to "I eat too much money to be on a diet." This line cleverly plays on the idea of having so much money that it's almost a burden, highlighting a lavish lifestyle. It's an interesting and less common way to refer to money, making it memorable for learners.
"Chargé" is a hard-charging French rap track by Niska, built around the chorus "chargé, fusil, shooter" (loaded, rifle, shooter), which sets the tone for the rest of the song.
Niska raps about wealth, ambition, and the street life he's come from, comparing himself to Pablo Escobar and El Chapo, and to Tony Montana from Scarface, while boasting about gold records and a lifestyle built on hustle. Tension with the police runs through the whole track, and the verses move fast between flexing about success and describing the danger that still surrounds him.
It's a snapshot of French street rap at its most confrontational, full of slang and local references from the Paris suburbs.