An easier way than worrying about the concept of countable and uncountable is to remember that 'many' goes with PLURAL nouns and 'much' goes with SINGULAR ones. For example you can say either: 'How much chocolate is there?' or 'How many chocolates are there?' In the first, you're thinking of chocolate powder or chocolate flakes, perhaps, so 'chocolate' is singular and you use 'much'. You can't say 'How many chocolate..?' In the second, you are thinking of individual chocolates in a box, which you might eat one by one, and so 'chocolates' is plural. You can't say 'How much chocolates..?' We use 'many' with plural words like men, women, children, people, countries, languages, books, apples... We use 'much' with singular words like money, advice, luggage, information, tea, water, apple juice.. That's all you need to know. Singular or plural.

I remember in English class at school, I was taught: Many, for amounts you can count e.g. "How many chocolates do you want?" Much, for amounts you can't count e.g. "How much sugar is needed?" (Can't be counted, only measured) This makes sense for other sentence patterns too: "There are so many cows!" Even though there are many, you can count them. "There is so much smoke." (Can't be counted, only measured)