Hi! I have a question . . .

I am a 66 yo heterosexual female and have been happily married for 41 yrs. I recently spoke with my younger sister who told me her youngest daughter now identifies as a non-binary homosexual. Admittedly, I know little about the LGBTQ+ community as I refrain from watching any news shows and do not involve myself in any social media. My question is, as a non-binary, my niece is feeling she is neither a male or a female, yet also saying she is a homosexual confuses me. Whom is she a homosexual with? Please pardon my lack of knowledge on this issue. I merely want to understand my niece. Thank you.