This sentence is grammatically incorrect, but it means: "What a good bonus/cousin!"
(It should be que buena prima for a female cousin and que bueno primo for a male cousin).
"bueno, tengo que..." means Good, I have to... [insert action here]
If you are asking what "que bueno no sabia que usted habla espanol" means, it's: "how nice I didn't know you speak Spanish"
It means: How good for you
How well you dance.
It means "How good it was to know you."
have goodnight ma'am
It is good that you are not working.
Very well, madam
Adjective: -que -qual de -bueno -lindo Pronoun -que Interjection -como
How good! In English we might say "How wonderful!" instead.
How great, something new.
It means, "What is there [that's] good?"