Does my backbiting or speaking ill of a certain nation mean that every individual from it will take from my good deeds on the Day of Judgment, and what can be done to expiate this sin?

Informing about certain peoples with bad characteristics is not backbiting unless it names known peoples. However, a Muslim should keep their tongue pure from mentioning the faults of people. If one of these peoples is present, it is not permissible due to the harm it causes, or if this is mentioned in the context of speaking about a specific person, then it becomes backbiting at that point.