Japanese is an extremely contextual language. A lot of the common phrases people know like “konnichiwa” and “arigatou gozaimasu” actually mean completely different things.
I read an example where a person went to the reception and asked to see someone. The receptionist replied with “失礼ですが”. The literal translation is “It is rude, but…” In this situation, it actually means the receptionist is asking for their name. Isn’t that strange? “shitsurei desu ga” and “sumimasen” both basically mean “excuse me,” but the former is used when asking things about the addressee. The latter is used when asking the addressee to do something.
In addition, those words like “konnichiwa” are actually shortened versions of full sentences. 今日は is actually part of a longer sentence which goes something like, “as for today, how are you?” But that’s implied by context, and now it has just turned into a greeting.
I also learned that emoji is actually a Japanese word, 絵文字! I guess it seems obvious when you know that kaomoji (顔文字) is a very obvious japanese word, but I never really thought about it.