Most native speakers (except for linguists and teachers of ESL) never think about "countable" and "uncountable" nouns. I had never heard those terms until I started tutoring ESL students (I was a volunteer; I never had formal training to teach.) A young child might make the mistake of saying "how much books" instead of "how many books," but an adult would just naturally choose the way that "sounded right" without stopping to think "Let's see -- is 'book' a countable or uncountable noun?"
I'm sure there are things in your native language, whatever it may be, that come naturally to native speakers but have to be explained by rules to foreigners who are learning your language. My guess is that grammatical gender is like this for many people. For instance, if I wanted to write something in French I would have to check a dictionary to find out if a word was masculine or feminine, while native speakers of French would just know without even thinking about it.