Poetry presents more of a rhythm and story rather than a conversation or dialogue. With poetry you can picture what the writing is saying due to the way they are written.
The tone in the last stanza is regretful. The poem is about a man who received advice from a wise man that he can give away all his wealth but not his heart. He's told that once you give away your heart, you lose it and end up regretting it. He experiences it and regrets afterwards.
It’s his imagination. this is the point in the story where macbeth is starting to experience paranoia (and almost insanity). banquo’s “ghost” is a creation from macbeth’s conscience that is sending a message that macbeth maybe shouldn’t have killed him.
