Much, many and a lot of are used when there is a large quantity of something.
Much and many are used in negative sentences and questions. They are not used in positive sentences.
Many is used with countable nouns.
- I don’t have many CD’s now.
(Negative sentence and CD’s is countable.) - How many brothers and sisters do you have?
(Question and brothers and sisters is countable.)
Much is used with uncountable nouns.
- Is there much milk in the fridge?
(Question and milk is uncountable.) - They don’t have much money to buy food this week.
(Negative sentence and money is uncountable.)
A lot of is used with positive sentences. It is used with both countable and uncountable nouns.
I have much money.
(The sentence is positive so we can’t use much.)- I have a lot of money.
- There are a lot of umbrellas for sale.
(Umbrellas is countable and the sentence is positive because it will be easy to buy one.) - I have a lot of time to help you.
(Time is uncountable and the sentence is positive.) - Do you have a lot of motivation?
(Motivation is uncountable and the sentence is a question.)