M'éprendre is a reflexive verb that means 'to fall for' or 'to become smitten with' someone. It's a more formal and poetic way to express falling in love than common phrases like 'tomber amoureux'.
In the song, Barbara Pravi repeatedly asks, "Mais quel mal m'a pris de m'éprendre de Louis?" (But what evil took hold of me to fall for Louis?). This elegant phrasing adds a touch of dramatic introspection to her declaration of love, making it a memorable and emotionally charged word.
"Louis" is Barbara Pravi singing about an infatuation that knocked her sideways. She opens by naming it plainly: "Louis, c'est inouï tout ce qui m'arrive" [Louis, it's unbelievable, everything that's happening to me]. The pull is physical too. One night with him, she says, was enough "Pour que mon corps sache qu'il est en vie" [for my body to know it's alive].
The chorus lays out what she's ready to trade: "Je donnerais mon âme / À la chaleur de tes mots" [I would give my soul / for the warmth of your words], and her heart "s'enflamme" [catches fire] every time she says it. By the end she's turned the question on herself, repeating it twice as the song closes: "Mais quel mal m'a pris / De m'éprendre de Louis?" [But what came over me, to fall for Louis?] She never actually answers it.