Misuse of Many

For countable nouns, use the term, “many”. For uncountable nouns, use the term, “much”.

I can’t attend the party because I have too many stuff to do.

Stuff is an uncountable noun, so it can’t be used with the adjective many.

I can’t attend the party because I have too much stuff to do.

Some nouns can be countable or uncountable.

There are many wines for sale.

This sentence refers to the different types of wine which are available for sale.

There are many wine for sale.

There is much wine for sale.

This sentence refers to the quantity of wine which is available for sale.