YOU SAID:
Hi i am a 12 year old girl
INTO JAPANESE
こんにちは私は12歳の女の子です
BACK INTO ENGLISH
Hello I am a girl of 12 years old
INTO JAPANESE
こんにちは私は12歳の女の子です
BACK INTO ENGLISH
Hello I am a girl of 12 years old
That didn't even make that much sense in English.