Much and many are used when there is a large quantity of something. They 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.)
For positive sentences we use a lot of. It is used with 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.)