The Collins Dictionary is an excellent resource. pish https://www.collinsdictionary.com/dictionary/english/pish exclamation 1. an exclamation of impatience or contempt verb 2. to make this exclamation at (someone or something)

You made a mistake when wrote “explain me”. You have to write “explain to me” it’s much more correctly)

James! I corrected my question. Could you read it again?

Hello John, where did you encounter this word? It would help to have the context. If you found it in all capital letters it is almost definitely an acronym. Meaning each letter signifies a word (i.e. USA = United States of America) Please include the context and I am happy to help you.