The english equivalent would be the order of adjectives before a noun. It is almost always in a very specific order, and nobody knows why. Think of a yellow big ball. It sounds wrong, and it should be a big yellow ball.
The difference between a or an does make sense, and it's the same as between pronouncing the like the or like thee. It changes based on whether the first letter of the word is a vowel or not
Only English speaking people that aren't bilingual would ask this question, no offense. This is like asking if I remember if some thing is der/die/das. Of course I do. I was raised with it. The closest example I can think of for English-speaking people is, would it sound correct to you if someone said "a apple" instead of "an apple"? I should hope not as it sounds wrong to me, and I've been bilingual from birth. It's the same thing.