When learning another language, you will ultimately come upon words that are difficult to translate. This isn’t because of some magical insight or a concept that "English just doesn’t have", it just comes from that different people will express things in different ways, and because of this different phrases and constructions become popular. In some cases, those terms can get borrowed, though even in borrowings meaning sometimes change (which gives me an idea for another post). And less closely related languages and languages coming from far separated cultures are likely to have more of these differences.
Chinese, of course, is full of terms that don’t have a clean English translation. You could write a book on chengyu (成语), the literary idioms that appear often in print and occasionaly in speech (in fact, I hear there are chengyu dictionaries), or about the poetic dish names seen on many Chinese menus. Some of these interest me enough that I want to borrow them, either because they seem to fit into a broad space covered by many different English words or because they cover culture-specific ideas that aren’t as easy to deal with using native terms. Here are a few of those terms:
1 事(情) "shi4(qing2)" Often glossed as "matters", "affairs", or "buisiness". 事情 is basically stuff that you do, or that occupies your time. For example, if someone asks you to dinner, but you have other things to do (you have to work, study, see another friend, etc.) one response is 我有事 "I have shi", or 我有事情要做 "I have stuff to do". Shiqing can be used in other ways as well. Asking 什么事？ "What shi?" is basically equivalent to "What’s up?" (In the more serious sense of "What’s wrong?" or "What do you need?", this isn’t an acceptable greeting, but that’s another post.) So in a way, it’s not just abstract stuff that you do (work, school, etc), but also abstract stuff that affects you.
2 境况 "jing4kuang4" Literally "circumstances" or "state of affairs". This is notable not so much in it’s meaning (which translates fairly well), but in usage. Chinese seems to use it a lot more than English, making a literal translation sound more formal than it actually is. One speech topic in my kouyu book was 说你家里的境况 "Talk about your family circumstances." Translated literally, that sounds like a psychologist’s question about family relationships, but in this instance it was really just basic information: How many siblings/children? What do your parents do? Where do you fall in the family tree? etc.
3 厉害 "li4hai" This is a favorite term for a lot of foreigners. When you look up 厉害 in a bilingual dictionary, some of the first translations are "difficult", "terrible", or "hard to deal with", which confused me slightly the first time a Chinese told me 你很厉害. in reality the meaning is much broader, basically just "extreme" in whatever way makes sense according to the context. So a test that is lihai is probably very difficult, but for a person it could be they are very talented, smart, or athletic depending on what exactly you are complementing. For instance, I have met an Australian guy here who speaks Mandarin fluently (to the point that he can tell funny stories and people laugh — I can’t do that) and knows several forms of martial arts. He is lihai.
4 功夫 "gong1fu" Everyone knows Kung Fu refers to Chinese martial arts. However, in Chinese the meaning of gongfu is much, much broader than that. It actually means "skill" or "hard work". For instance, you may hear a Chinese person say 我花了很多功夫… "I spent a lot of gongfu…" to mean that it took a lot of effort to reach whatever goal he was reaching for. You can also talk about your "soccer gongfu" (足球功夫) or "calligraphy gongfu" (书画功夫), or any other skill that must be improved through lots of time and effort (as such, Linux Kung Fu seems to use the term in the Chinese sense).
5 关系 "guan1xi1" Most people familar with China and Chinese culture already use this term. Literally it translates as "relationship", but when borrowed it’s usually used for a more specific meaning something like "connections". I think all cultures have some concept of using connections or personal relationships to get things, but in Chinese culture it has a certain emphasis, partly stemming from the importance of interpersonal relationships in Confucian philosophy and partly because of a society that still lacks somewhat in government services and rule of law.
6 华侨 "hua2qiao2" "Chinese diaspora" or "overseas Chinese". -桥 can be added to any single-character nationality (and maybe some phonetic multi-character ones) to refer to people from that country or with ancestry from that country living in other parts of the world. Many of the friends I have made here are huaqiao, raised in Germany, Italy, or the US but born to Chinese parents. Some of them are more Chinese and others are more German, Italian, etc, for various reasons.
7 方言 "fang1yan2" Often translated as "dialect", though I have read an interesting argument for translating it as "topolect" instead. It most commonly is used to refer to the "regional dialects", or rather the various Chinese languages and their local variants in different cities. The reason I bring up the "topolect" translation is that if you mention a fangyan you’re probably referring to a particular place. Not as many people will know about Wu or Min than know about Shanghainese or Suzhouhua (both variants of Wu), or Fujianese or Taiwanese (Min variants).