"She is the world's most beautiful girl!" and "You are the most beautiful girl in the world!" are English equivalents of Lei è la ragazza più Bella del mondo! Context makes clear whether the singular personal pronoun and present indicative, feminine singular definite article and noun, comparative/superlative, feminine singular adjective, preposition and masculine singular definite article, and masculine singular noun reference the formal second person (case 1) or third person (example 2). Regardless of meaning or use, the pronunciation will be "LEH-ee eh la ra-GAT-tsa pyoo BEL-la del MON-do" in Italian.
"You're the most beautiful girl in the world" is an English equivalent of the Italian phrase Sei la piùbella ragazza del mondo.
Specifically, the verb sei is "(informal singular you) are". The feminine singular definite article la means "the". The comparative/superlative più means "most" in this context. The feminine singular adjective bella means "beautiful, handsome, nice, pretty". The feminine noun ragazza means "girl, girlfriend". The word delliterally means "of the", from the combination of the preposition di ("of") and the masculine singular definite article il ("the""). The masculine noun mondo translates as "world".
The pronunciation will be "SEY la pyoo BEHL-lah rah-GAHT-tsah dehl MOHN-doh" in Italian.
La bella in Italian means "the beautiful" in English.
La vita è Bella
Sei la ragazza più bella! in Italian means "You're the most beautiful girl!" in English.
la nostra bella amicizia
"This is beautiful music!" in English is Questa è la bella musica! in Italian.
Bella donna in Italian means "beautiful woman" in English.
Bella tu is an Italian equivalent of the English phrase "beautiful you." The pronunciation will be "BEL-la too" in Italian.
Bella la vita insieme
"The most beautiful" in English is il più bello in the masculine and la più bella in the feminine in Italian.
"The beautiful path" is one English equivalent of the Italian phrase la via bella. Specifically, the feminine singular definite article la is "the". The feminine noun via means "path, road, way". The feminine adjective bella translates as "beautiful". The pronunciation will be "la VEE-a BEL-la" in Italian.
E' Bella la vita insieme a te.
'Beautiful Spain' is an English equivalent of la bella Spagna. The feminine singular definite article, adjective, and noun translate literally into English as "the beautiful Spain." The pronunciation will be "la BEL-la SPA-nya" in Italian.