Paupières translates to "eyelids". While seemingly simple, it's a word that carries a lot of poetic weight and isn't as common in everyday song lyrics as more direct emotional terms.
In the song, Pomme sings, "Si la tristesse me défie, Sous mes paupières fait son lit" (If sadness defies me, Makes its bed beneath my eyelids). This imagery is incredibly evocative, personifying sadness as something that settles in the most intimate and vulnerable part of her being, just behind her eyes. It's a beautiful and slightly melancholic image that makes the word memorable.
"Comme tu dis" is Pomme's quiet pep talk to herself. She admits how fragile her confidence feels: no friends to lean on, tears mixed with laughter, sadness settling in under her eyelids like it has found a permanent home.
Against all that, she holds onto one thing: someone else believes in her. The chorus repeats it like a mantra, "I'll try to believe in myself, like you say you believe in me." She isn't there yet. She's still practicing. But borrowing someone else's faith is enough to start.
By the end, she has learned the words by heart, even as her fears stay close. It's a song about how trusting yourself can begin with trusting that someone else already does.