Qual é a diferença entre "hear about" e "hear of" ?Podes indicar apenas respostas exemplo.

They generally mean the same thing. About can always be replaced by "of" but sometimes it sounds too formal and weird.

I've heard about him/it = I've heard of him/it ("heard about" someone is less used for people unless you mean to imply something happened to him. "Have you heard about Lily? No, what happened?")

I know about it
I know of it ('Know of' can sound a bit formal but it's generally fine)

The speak about it
The speak of it (Speak of is more formal again)

Talk about it
Talk of it (You can still technically say "talk of" but you'll never hear or say it because "of" is formal and "talk" is informal so they sound very strange together. In this case just use "about."