Cooking and preparing

The list a recipe is carried out with. Near the end of it is les restes, and the plural is doing all the work. Le reste in the singular is whatever remains of anything at all — le reste du groupe, le reste de la journée, fais le reste demain. Put it in the plural and it narrows to one thing: les restes is the food left after a meal, and on mange les restes ce soir means exactly what an English speaker would call leftovers. Nothing else changes — same word, same article pattern, and the s is silent, so in speech only the article tells you which one you heard. English has no such pair: « the rest » never means food, « leftovers » is a separate word that has no singular, and « the remains » belongs to archaeology or to a body. Two lexemes on one side, one noun and a number on the other.