L'échine refers to the spine or the back, often used in a more literary or slightly archaic context than the common word le dos.
In the song, the lyric "Quand la vie me fait courber l'échine" (When life makes me bend my back/spine) vividly expresses a feeling of being weighed down or humbled by life's difficulties. It's a more evocative and less common choice than le dos, making it stand out.
Jérémy Frerot's "Tu Donnes" is a beautiful song about finding strength and comfort in someone else, especially when life gets tough. He sings about moments "Quand je perds le nord" [When I lose my way] and "Quand la vie me fait courber l'échine" [When life makes me bend my back], describing how winter can even "dévore Mon esprit jusque dans les abîmes" [devour my spirit into the abyss]. It's in these dark times that the other person's presence becomes a gentle solace.
What's truly touching is how this person gives so much just by being themselves. Jérémy sings, "Rien qu'en riant, tu donnes" [Just by laughing, you give] and "Rien qu'en étant là tu donnes" [Just by being there, you give]. It's not about grand gestures, but the simple, precious act of existing and sharing their positive outlook. When they say, "Ça ira va t'inquietes pas" [It'll be okay, don't worry], it genuinely helps him believe that "Il peut tout arriver" [Anything can happen] when he sees life through their eyes.