Greek to you, Sanskrit to me: What do phrases like 'hot potato', 'bone of contention' mean?

Mary: John, What’s up?
John: Not much. What about you?
Mary: Everyone has been talking about the New Education Policy and I think it is good to discuss it.
John: Yes. It’s a hot potato.
Mary: Hot potato? What do you mean?
John: Any controversial issue or subject that people disagree strongly about is called a hot potato.
Mary: In the case of NEP, not all people disagree about it.  
John: It is a political hot potato.  Almost all politicians talk about it. Some support the policy document and some oppose it tooth and nail.  That’s why it remains a controversial issue.
Mary: Are there any other expressions for ‘hot potato’?
John: We can also use the expression ‘the bone of contention’. An issue over which there is continuing disagreement is called the bone of contention.   NEP draft was the bone of contention during the past year and it continues to be controversial even after the Union Cabinet has approved it.
Mary: Can we say that the three-language formula is the bone of contention between the Central and some state governments?
John: Yes, you have hit the nail on the head.
Mary: Oh, thanks.  It is because I have been reading a lot about this issue nowadays.
John: Yes, the three-language formula is the talk of the town.
Mary: Talk of the town?  Do you mean that it is discussed by everyone?
John: Yes, absolutely correct.  That’s is the topic discussed almost by everyone. It is being discussed in both mainstream and social media across the country. I must say it is the talk of the country.
Mary: I heard that Tamil Nadu is totally against it.  Why is it so?
John: Tamil Nadu has been opposing the three-language formula since 1968. People of the state think that the Central government is trying to impose Hindi on them.  They fought tooth and nail opposing the language policy and as a result, the only two-language system is followed in the state.  
Mary: Do you mean that the people of Tamil Nadu went out of their way to oppose it?
John: Absolutely correct.  Even now the Tamil Nadu Chief Minister K Palanizwami has taken a strong exception to the 3-language formula proposal and has made it very clear that the state government will never allow the language policy.
Mary: Sounds interesting!  
John: The Chief Minister has to show that he strains every nerve.
Mary: What?  Why should the Chief Minister strain his nerve? What do you mean?
John: ‘To strain every nerve’ is an idiomatic expression that means to make the greatest possible effort to do or to stop something.
Mary: Yes, he has to prove that he is working in the interest of the people of Tamil Nadu.
John: Let’s not get into politics.  
Mary: Do you think politics is a dirty word?
John: No. It is a beautiful word.  But it is good not to talk about party politics now. By the way, did you read about the controversy regarding the promotion of Sanskrit in the New Education Policy?
Mary: What’s it about?
John: The NEP document states that Sanskrit is an “important, enriching option” for students.  
Mary: Important and enriching option?  That’s Greek to me.
John: In the Indian context, you should say, “It’s Sanskrit to me.”
Mary: You have hit the nail on the head, John.