This is the 1578th most frequent Russian word.
скорой
"Скорой" means "fast" or "quick" when describing something, or "urgent" in the context of emergency services (e.g., ambulance).
In this sentence, 'скорую' is used to refer to 'an ambulance' as a noun in the accusative case, aligning with the action of calling it.
Я вызвал скорую помощь.
I called an ambulance.
Here, 'скорой' is an adjective in the instrumental case modifying 'подготовки,' indicating 'quick' preparation.
После скорой подготовки мы начали выступление.
After quick preparation, we began the performance.
In this instance, 'скорую' is an adjective in the accusative case modifying 'встречу,' implying an anticipated 'quick' meeting.