This is the 345th most frequent Vietnamese word.
sự
The Vietnamese word "sự" translates to "affair," "matter," "event," or "act" and is used to form abstract nouns.
In this sentence, "sự" is used to create an abstract noun from the adjective "thành công" (success), referring to the state or quality of being successful.
Sự thành công của anh ấy thật đáng ngưỡng mộ.
His success is truly admirable.
Here, "sự" serves to turn "cố gắng" (effort or striving) into a noun to express the concept of making an effort.
Chúng tôi luôn đánh giá cao sự cố gắng của bạn.
We always highly appreciate your effort.
"Sự" is utilized to form an abstract noun from "bất ngờ" (surprise), emphasizing the event as a noun.