“My mother she is nice” is incorrect. The correct way to say it is “My mother is nice”. You cannot put the “she” there, since we already know the mother is the one who’s being talked about.
The provided sentence "My mother she is nice" is incorrect for a few reasons. First of all, the sentence does not end in a period. Second of all, you would not say <em>My kitten she is playful.</em> would you? no, you would not. When speaking in English, you do not place a noun (a person in this case) next to a pronoun since you already have the noun to identify the character with.
