Meaning of the quote.

Hi guys,

I am Soma.
This is my first post on this forum. I know it is funny as the show has ended now.
But I was wondering what this quote really means?

" He who practices truth without knowing the difference between truth and falsehood is a fool"

Krishna to Arjun

What it actually means? Can anyone explain this to me with an example.

he means you must know the truth, the difference between good and bad, the knowledge to contemplate what truth is and what false is. a simple example would be the dyut sabha, yudhishtir was a fool because he practiced the truth without knowing the difference between what truth actually is and what false is. morally it is wrong to stake your wife and watch her being stripped naked. but the truth was as a samrat he could stake his wife and as a daas he had to obey orders. so what krishna meant was, one must ask oneself if they really know what truth is before speaking it or preaching it or acting it out. was yudhishtir following dharma for real?