Questions & Answers about من یک راز بزرگ دارم، اما نمیگویمش.
Where is the word for "it" in نمیگویمش?
It is the ش ending at the very end of the word! The verb is نمیگویم (I am not saying), and attaching the pronoun suffix -esh turns it into "I am not telling it". This is exactly how object enclitics work: they can attach directly to the end of a conjugated verb.
What is the base verb for نمیگویمش? It looks very different from the infinitive for "to tell".
The infinitive for "to say" or "to tell" is گفتن (goftan). In the present tense, its stem changes completely to گوی (guy). So to build "I am not telling", we combine the negative present prefix نمی (nemi-), the stem گوی, and the "I" ending -َم (-am).
I learned the suffix for "it" is -ash. Why is it pronounced -esh here?
In formal Farsi, the suffix for "him/her/it" is indeed pronounced -ash. However, in everyday spoken Farsi, it softens to -esh. Because this sentence is conversational, it is usually pronounced as nemiguyamesh. Both versions are spelled exactly the same way.
How are "secret" (راز) and "big" (بزرگ) connected in this sentence?
In Farsi, adjectives almost always come after the noun they describe. They are linked together by an invisible "e" sound called the ezafe. So "a big secret" is pronounced yek râz-e bozorg.