This is the 675th most frequent Persian word.
گفتنی
"گفتنی" means "noteworthy" or "worth mentioning."
In this sentence, 'گفتنی' is used nominally, indicating 'noteworthy content or things worth saying'.
او درباره مشکلاتش گفتنیهای زیادی داشت.
He had many noteworthy things to say about his problems.
In this case, 'گفتنی' serves as an adjective describing 'a story worth telling'.
داستان او آنقدر گفتنی بود که من با دقت گوش دادم.
His story was so worth telling that I listened carefully.
Here, 'گفتنی' functions adjectivally in an impersonal construction, representing 'worth mentioning'.