用英语说，懂你的人不必解释，不懂你的人解释也没用。

You needn't explain it to the person who understands you.It's no use to explain to the person who doesn't understand you.

if the person know you well, you don't have to explain anything; but if someone does not understand you, it is no point to explain anything

You don't have to explain to the people who can understand you .lt's no use to explain to the one who can't understand you .

"People who understand you don't need to be explained to, and those who don't understand you won't be helped by explanations."

The people who understand you don't need explanations, and those who don't understand you, explanations are useless.