I means "your world".
"tu as quel âge" mean "how old are you" ;)
Assuming you mean tu sabes, it means "you know"
The crazy world
"Tu haces" means "you make".
"Tu hermana" means "your sister."
"Tu eres mi mundo" in English means "You are my world."
"You are your mother's whole world".
El mundo es su mundo or El mundo es tu mundo
You are the most beautiful girl in the world.
"Tu eres el mundo"
Du bedeutest mir alles.Given the nature of the sentence it is highly unlikely that the formal Sie-form would be used.
Tu eres mi Mundo
Translation: You were the prettiest angel in the entire world.
tu eres la mejor novia en todo el mundo tu eres la mejor novia en todo el mundo
Su / tu / vuestro mundo es éste. With different possible syntactic collocations
"And the world is so ugly you are the (girl) child of my heart."
mejor madre en el mundo