what is exactly the meaning of two words "Good" or "Bad"? why We judge everything/everyone in our life by labelling with "Good/Bad" "Better/Worse"? is there really exist any Best or worst thing in the universe?

Well of course "good" and "bad" are both very subjective. It's all about perspective. Yes it is true that many of us judge everything by "good" or "bad", but one might say something is the worst thing ever, and another might say its the best thing ever. So in my opinion, "worst", "best", "good", "bad all come down to perspective and how we see things.