1. "They're nice" means: They are friendly.2. Nice is an adjective that means: precise, beautiful, subtle, and kind.3. Phrases using "nice": - Have a nice weekend. - Have a nice trip. - Have a nice time. - It was nice talking to you.4. Example sentence: I've met your father and he's rather nice.Nice is used in greetings, such as when meeting someone for the first time: "It's nice to see you." When leaving, it can be followed by a present participle ("meeting") or a past participle ("to have seen").In the structure "nice and + adj.", "nice and" is used to emphasize the degree of the following adjective, meaning "very" or "extremely," commonly used in speech and placed after the word it modifies. It can also be used ironically, equivalent to "quite" or "very."The phrase "nice of sb to-v" is used to express gratitude for a kind act performed by someone.When "nice" means "respectable" or "prudent," it is typically used in negative sentences.Differential sense of "nice," "decent," "decorous," "proper," and "seemly":- Decent refers to something that keeps within the limits considered suitable for its kind or class, appropriate from a moral or social-etiquette point of view, or in keeping with high taste or a particular situation.- Decorous describes something marked by politeness and sometimes formal or ceremonial correctness.- Seemly means not only appropriate and proper but also aesthetically pleasing.- Proper indicates conformity to generally accepted ethical or social standards or customs.- Nice suggests a level of excellence that meets standards of behavior, manners, and language that are very strict or demanding.