YOU SAID:
Onesan watashi kawaii desu
INTO JAPANESE
おねさんたちかわいいかわいいです
BACK INTO ENGLISH
My sisters are cute
INTO JAPANESE
私の姉妹はかわいいです
BACK INTO ENGLISH
My sister is cute
INTO JAPANESE
私の妹はかわいいです
BACK INTO ENGLISH
My sister is pretty.
INTO JAPANESE
私の妹はかわいいです。
BACK INTO ENGLISH
My sister is pretty.
That didn't even make that much sense in English.