The problems English speakers have when dealing with adjectives (describing words) in French (and most other foreign languages) stem from the concept of adjectives having to change to ‘agree’ with what they are describing. There is also the question of where to put the adjective. No such head scratching in English, adjectives don’t agree and always come before the word described e.g. a fat girl, a fat boy, two harassed book publishers etc. Once again, it’s really English itself which is the cause of the angst.
Let’s deal with agreement first. Actually, come to think of it, we do make one adjective agree and that’s ‘blond’ which we make ‘blonde’ when it describes, as it usually does, a woman. I can’t think of another.
The usual way to make adjectives agree is to add an ‘e’ for feminine and an ‘s’ for plural so you’ll put ‘es’ for feminine plural. But, wouldn’t you know it, there are very many irregular ones e.g mad = fou (m) but folle (fem); old = vieux (m) but vieille (fem). What an unnecessary complication which adds nothing to the meaning. Boney French will sort this out for you!
I said above that all adjectives in English come before the noun, but this isn’t strictly true. There are quite a few which come after: court martial, battle/Princess Royal, arms akimbo, attorney general.
Some French adjectives come before the noun, some after. You just have to learn them. BUT, if you get them the wrong way around or don’t make them agree, it doesn’t matter a sprout. You will be understood and may get a free lesson when your French friend corrects you.