Buon compleanno, Sorella! is an Italian equivalent of the English phrase "Happy birthday, Sister!"
Specifically, the masculine adjective buono* literally means "good". The masculine noun compleanno means "birthday". The feminine noun sorella translates as "sister".
The pronunciation will be "bwohn KOHM-ple-AHN-noh soh-REL-lah" in Italian.
*The final vowel drops before a noun which begins with a consonant.
"Beautiful horse" in English is bel cavallo in Italian.
"Beautiful night" in English is bella notte in Italian.
"Beautiful disaster" in English is bel disastro in Italian.
"Beautiful mountains!" in English is Belle montagne! in Italian.
"Beautiful walls!" in English is Bellissime mura! in Italian.
"Beautiful mommy!" in English is Bella mamma! in Italian.
"Beautiful Rome!" in English is Bella Roma! in Italian.
"Beautiful woodland!" in English is Bel bosco! in Italian.
"Beautiful moments!" in English is Bei momenti! in Italian.
"Beautiful nephew" in English is bel nipote in Italian.
"We are very beautiful!" in English is Siamo bellissime!in Italian.
"Beautiful dream" in English is bel sogno in Italian.