Not all languages, not just Japanese, can be translated perfectly into other languages. Words used as conversational expressions are especially prone to misunderstandings due to differences in nuance and range of meaning. No one wants to be embarrassed by a misunderstanding, so speaking a second language can be an emotionally taxing task for anyone.
To help relieve some of this anxiety, I will introduce the meanings of three complicated conversational phrases that Japanese people often use, along with specific examples. Building up your knowledge of these conversational phrases will not only help you in your conversations but will also help you deepen your understanding of the Japanese books, movies, games, animes, etc you already know.
普通だった – “decent” or “boring”?
The word 普通(ふつう) is a complicated word that can mean high, low or no interest. It's like the English words "normal," "ordinary," and "average" all in the same word. For example, if you ask a Japanese person who went to a new restaurant what he thought of it, and he replies,「普通だった」. This answer itself can have three different meanings: "It was decent even though I didn't expect it to be (high evaluation)," "It was boring even though I expected it to be (low evaluation)," and "I didn't feel anything in particular (indifference). In order to determine the meaning, you need to pay attention to the context, the actual quality of the restaurant, and the speaker's personality. Likewise, when you use the word, you have to be careful not to mislead others. You need to be careful about the way you say it and the tone of your voice so that the intended meaning is conveyed. The word 普通 is relatively casual, so it is best not to use it in formal situations.
verb + つもり – Noun used like modality
If you look up the noun つもり in the dictionary, you will usually find three or more completely different meanings, and you will end up not knowing what it means. Although つもり is a noun, it is an expression like a modality, and when used in conversation, it has three main meanings: intention, conviction, and assumption. It is used after dictionary form of a verb, as in 「旅行に行くつもりです」(I intend to go on a trip), and implies "intention" when talking about the future. When it is used after the Ta-form of the verb, it means either "conviction" or "assumption". The meaning is "conviction" in a realistic situation, such as 「買ったつもりだった」(I thought I bought it), and "assumption" in a figurative situation, such as 「猫になったつもりで」 (Let’s assume you are a cat,). There are exceptions, of course, but just remembering this trend will make it easier to predict the meaning. As an aside, つもり is sometimes written in kanji in dictionaries (積もり), but it is more commonly written in hiragana.
かわいい + noun – Not as “cute" as you'd expect
The word "kawaii" is now accepted as an English word, but the Japanese word かわいい does not necessarily mean "cute". The word かわいい has both positive and negative meanings, such as "cool, immature, trivial, genuine, small, unusual" etc. There are no restrictions on the target of the adjective. For example, かわいい服(ふく) is often a complement to pure cuteness in appearance. However, かわいい性格(せいかく) is usually interpreted as "sincere” and “genuine”. The term かわいい問題(もんだい) means "a minor problem" and is often used in comparison to the more serious issue at hand. The word かわいい is also used to praise a cool design, to describe something smaller than it needs to be or to critique the immaturity of someone's words or actions. Also, even if it is meant to be positive, the act of directly telling someone of the opposite sex or superior that they are かわいい can be considered rude.
As you can see, conversational phrases in Japanese are often polysemous and ambiguous. When looking up the meanings of Japanese phrases, the Internet is a useful self-study resource, but there is often too much information to be certain of what is the correct answer. The most efficient way to study Japanese conversational phrases is to alternate between self-study and asking questions to native speakers to build up practical knowledge.