Milk is an uncountable noun. It is not possible to say a milk or milks. The articles a and an are normally not used before uncountable nouns such as olive oil. You can use some instead:
Fry the vegetables in some olive oil.
The article the can be used with uncountable nouns, e.g. water when they are specified by the context:
Is the water boiling yet?
| Quantifiers with countable nouns: | |
|---|---|
| many | I bought many carrots. |
| more | I bought more carrots. |
| most | I bought the most carrots. |
| a few/some | I bought a few useful tools. |
| few | I have few friends. |
| fewer | He has fewer friends. |
| fewest | She has the fewest friends. |
| Quantifiers with uncountable nouns: | |
|---|---|
| much | There is too much flour in the bowl. |
| more | There is more flour in the bowl. |
| most | There is the most flour in the bowl. |
| a little/some | Do you want a little help with hanging the laundry? |
| little | The food has little protein. |
| less | The food has less protein. |
| least | The food has the least protein. |
In spoken language it is common to use the expression a lot of/lots of/plenty of instead of much or many:
I like to put a lot of mustard on my hot dog.