YOU SAID:
I do not understand what you are telling me.
INTO JAPANESE
私はあなたが私に話しているものを理解していません。
BACK INTO ENGLISH
I do not understand what you are talking about me.
INTO JAPANESE
私はあなたが私について話しているものを理解していません。
BACK INTO ENGLISH
I do not understand what you are talking about me.
That didn't even make that much sense in English.