The word you cannot translate easily may contain a habit your language takes for granted.

A word with no clean equivalent usually marks something one group of people does often enough to need a name for it. The difficulty is not really vocabulary; it is that the surrounding habits differ. When you meet a word like that, you are being shown a practice rather than just a term.

If you are learning a language, collect the words that resist translation and ask what people actually do when they use them. The same trick works at home with the jargon of a family or a workplace, where the untranslatable words often mark the customs nobody explains.