It means "(She) is a dirty whore/slut." It is very vulgar and should not be used in polite conversation.
you're an ass
That would translate to: tu eres un ciruela
Tonto and estupido both mean dumb or stupid in Spanish. However, if you're referring to a girl, replace the o on the end with an a. "Tu eres tonto" means "you're stupid".
you're a bit crazy really.
You are a funny guy
Translated to: "You are a lunatic."
You're a mouse
It says, "You are a bad friend."
You're a bold and fresh
you is an ugly donkey and you isn't a good girlfriend. Don't feel too bad about the insult though, it should read tu eres...tu no eres.
you're an ass
This means: "If you are a bird, I am one too".
It's not very nice at all. It means, "Still you are a dirty bitch whore haha"
"Tu estás un estrella" is grammatically incorrect in Spanish. The correct way to say "You are a star" in Spanish is "Tú eres una estrella."
Tu eres un buen estudiante.
That would translate to: tu eres un ciruela
Tú eres un super estrella means You are a superstar The statement is directed to a man or boy. Replace "un" with "una" to direct the statement to a woman or girl.