This is the 15177th most frequent Polish word.
saudyjskiej
"Saudyjskiej" means "Saudi" (adjective, relating to Saudi Arabia) in English.
In this sentence, 'saudyjskiej' is an adjective in the locative case, agreeing with 'ambasada' (embassy). It describes the embassy as belonging to Saudi Arabia.
Pracuję w ambasadzie saudyjskiej.
I work at the Saudi embassy.
Here, 'saudyjskiej' modifies 'kultury' (culture) in the genitive case, specifying that the culture belongs to Saudi Arabia.
Studiuję historię kultury saudyjskiej.
I study the history of Saudi culture.
In this example, 'saudyjskiej' describes 'polityce' (politics) in the locative case, indicating the subject the book covers related to Saudi Arabia.