Từ dụ is a word that people use when they want to describe or talk about something in a way that is not very clear. Think of it like a secret code that only certain people understand.
Let's pretend you and your friend are playing a game and you want to tell them a hint, but you don't want anyone else to understand. You might use a word or phrase that only you and your friend know the true meaning of. This is kind of like what people do when they use từ dụ.
It's like a secret language for describing things without being too obvious about what you're talking about. So, if someone says a sentence with a word that you don't know, it might seem like meaningless jibberish to you, but to someone who knows the secret meaning, it can communicate a lot of information.
Overall, từ dụ can be confusing if you don't know the secret meaning, but it can also be a way for people to talk in code or keep secrets.