I am Chinese and I can do some translation. I have no idea what the monkey (猴子 Hóuzi) refers to, I think it's a player in-game name and what Duang is though.
Translation:
To list a simple example, suppose we hammered 400 production into a Wonder, then cut into a Monkey, at the end of the turn* (Duang???), in an instant, Monkey receives a 200 production overflow and even retained 170 production. Actually, on the turn when you saw that everything else seemed very cheap to produce, you were looking at it with an excess of 170 production. This excess production was then removed because the city lacked any target for production for that turn the overflow existed.
What I think it means:
A player missed a 400 production wonder and 200 production was retained. 30 of that 200 production was used to build something which is why the production seemed cheap since it was using the overflow of 200 production. However, even though there was an excess of 170 production leftover, the game completely removed the access production at the end of the turn and reverted it back to the city's turn-based output because there was no target being produced for that turn and cities cannot be idle in Civ 6.
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