This is the 292nd most frequent Croatian word.
jedne
"Jedne" means "of one" or "some" (feminine genitive singular form).
The word 'jedne' indicates that the bookstore is one specific entity among several or many available bookstores in the city.
Kupio sam knjige iz jedne knjižare u centru grada.
I bought books from a bookstore in the city center.
Here, 'jedne' applies to 'osobe' (person), used in a genitive form, indicating a particular person out of multiple possible individuals.
Pričala mi je o jedne osobe koju je upoznala na putovanju.
She told me about a person she met on a trip.
The word 'jedne' here modifies 'večeri' (evening), expressing a specific instance among many possible evenings.