This is the 12250th most frequent Russian word.
иранского
"Иранского" means "Iranian" (relating to Iran).
The word 'иранского' functions as an adjective in genitive case, describing 'писателя' (writer).
Я прочитал книгу иранского писателя.
I read a book by an Iranian writer.
In this sentence, 'иранского' modifies 'искусства' (art), indicating origin.
На выставке были представлены рисунки иранского искусства.
At the exhibition, there were representations of Iranian art.
Here, 'иранского' qualifies 'производства' (production), suggesting the country of manufacture.