This is the 2279th most frequent Polish word.
szybkie
"Quick" or "fast."
The word 'szybkie' is used here as an adjective in plural form, agreeing in gender and number with 'samochody' (cars).
Mam szybkie samochody.
I have fast cars.
Here, 'szybkie' is used as an adjective describing 'decyzje' (decisions), a feminine plural noun.
Szybkie decyzje są czasem konieczne.
Quick decisions are sometimes necessary.
The adjective 'szybkie' modifies 'reakcje' (reactions), which is also a feminine plural noun.