"He is rich."
Translation:Anh ấy giàu.
It's used when referring to another person. "Cô" (girl/lady/ma'am/etc.) is used by itself when referring to the [female] that is being spoken to, and "Cô ấy" is more like "that girl/lady" instead of directly referring to the person on the other end of the conversation.
Can "đó" be accepted instead of "ấy"? I'm used to the former and the latter I'm familiar with but shouldn't they be interchangable?