This is the 8561st most frequent Polish word.
promocji
"Promocji" in English means "promotion" (e.g., discount or marketing campaign).
The word 'promocji' is used here in the genitive case to refer to a sale or discount.
Skorzystałam z promocji w sklepie.
I took advantage of a sale in the store.
Here, 'promocji' is used in the genitive case to describe the sale being advertised.
Widziałem reklamę promocji na telewizor.
I saw an advertisement for a sale on a TV.
In this sentence, 'promocji' is again in the genitive case, indicating possession or relation to the word 'plakat' ('poster').