L'feu is a colloquial contraction of "le feu," which literally means "the fire." While "fire" is a common word, its usage in this song is particularly interesting because it's used as slang.
In the context of the song, "c'est l'feu" means "it's lit" or "it's amazing/great." Wejdene uses it to describe the intense passion and excitement she feels when she's with her loved one, especially when they are playing the "same game" in their relationship. This modern, idiomatic use of "feu" makes it a captivating word for learners.
"Le Feu" is a French pop love song about missing someone and craving their closeness. The singer calls out to a partner who feels too far away, asking them to call or come back, because being apart leaves her feeling cold and incomplete.
The title, "le feu" ("the fire"), is the song's central image: being with this person feels warm, alive, like fire, while being without them leaves her "un p'tit peu froid" (a little cold). The chorus repeats "avec toi, c'est le feu" (with you, it's fire) to capture how good the connection feels when they're together.
It's a simple, catchy way to talk about longing and physical closeness, using the contrast between warmth and cold to describe how much better everything feels with someone you love nearby.