What does pot calling the kettle black mean by describing people?

The word "pot calling the kettle black" comes from King Huiliang of Mencius, in which "pot calling the kettle black" refers to those who retreat fifty steps in the war, mocking those who retreat a hundred steps for cowardice. Some people once used words to describe it. Some people laughed at other people's shortcomings or faults, but did not reflect on their own shortcomings or faults, only to a lesser extent than others. "pot calling the kettle black" is a kind of performance without self-knowledge.