This is the 11159th most frequent Russian word.
готовящемся
"In preparation" or "being prepared."
In this sentence, 'готовящемся' functions as an adjectival participle describing the noun 'празднике' (celebration), meaning 'upcoming' or 'being prepared'.
Мы говорим о готовящемся празднике.
We are talking about the upcoming celebration.
Here, 'готовящемся' again acts as an adjectival participle modifying the noun 'спектакле' (play), emphasizing that it is in the process of being prepared.
Он рассказал о готовящемся спектакле в театре.
He talked about the upcoming play at the theater.
Similarly, in this sentence, 'готовящемся' modifies 'проекте' (project), indicating that it is in the preparation or planning stage.