Definition
This idiom is used to indicate that someone does not possess a particular quality or have experience with a specific activity, suggesting a complete lack of understanding of its meaning or importance.
不懂、缺乏某事物的真正含意（多用在否定句中）
You say he's good at managing finances? He doesn't even know the meaning of the word "budget."
你說他擅長管理財務？他甚至不知道「預算」這個詞的意思。
They criticize this policy for being unfair, but they do not know the meaning of the word "fairness."
他們批評這項政策不公平，但他們不知道「公平」這個詞的意思。
Some people talk about "sacrifice" all day, but they really don't know the meaning of the word.
有些人整天談論「犧牲」，但他們真的不知道這個詞的意思。