What does the phrase 'to take a good look at yourself' mean?

The phrase 'to take a good look at yourself' means that before judging someone because you think that they are doing something wrong firstly you should thought: "Maybe I am not better? Maybe sometimes I do wrong things too, and I should not blame each other for being not perfect?". Sometimes we forget that we all are human beings, and we all sometime can do mistakes, but it is not a reason to ruin relations. Firstly you should always "look at yourself" and understand, that you are a human too.