What does positive and negative connotation mean?
Aside from the literal meaning of the word, a connotation associated with a word is the emotions and feelings that people feel about it.
For example, you could call your friend an "idiot", and someone could think that you're insulting your friend just because the word "idiot" has a negative connotation, even if you don't mean it that way.
Just like saying, "Good job!" has a positive connotation of being a praise or encouragement because that is it's main use, even though someone can use it with distaste or sarcasm.