This is the 14570th most frequent Russian word.
пекинскую
"Пекинскую" means "Beijing" in the feminine accusative or feminine singular adjective form in English.
Here, 'пекинскую' modifies 'утку', specifying the type of duck as from Peking.
На ужин я приготовила пекинскую утку.
For dinner, I prepared Peking duck.
The word 'пекинскую' is used as an adjective referring to the cabbage as being of the Beijing type.
Мы заказали пекинскую капусту для салата.
We ordered Peking cabbage for the salad.
In this sentence, 'пекинская' describes the architecture, indicating a style or form linked to Peking.