What she's saying is that white feminists need to be aware of whose voices and experiences (current and historical) they are including or excluding when they talk about 'women' as a group.That's she links trans exclusion and racism in some current discourse
We should all be conscious that our own particular experience is not at the centre of everyone else's universe, nor does it relate, exactly, to everyone's experience......that doesn't invalidate arguments or campaigns by any particular groups of people, though. We all tend to campaign for things closest to our own heart and experience. Things which move us.
This 'white feminism' thing is a red herring as far as I'm concerned - and seems to stem from the politics of intersectionality - in which each group vies to be centred, in leagues of oppression. Not only does it highlight the difference between people & groups ( which is of course valid) but arguably it cements them in place, reinforces and upholds them.
The women's movement I know has always been about all women; and the sufferings of the the most marginalised the benchmark for how far we've come. Feminism for me has always been about recognising our common humanity; recognising our common condition as women. Of course some women are oppressed by their ow particular situations and conditions in a way which might not, necessarily, effect us personally - doesn't mean we cannot empathise and support.
What I see is that many women are caught in a conflict between their ethnic identity, and their position as women in those specific cultures, as well as in the world at large.
Womanhood is not an identity; being female is a fact that cannot be changed. Cultures can change though; people can break out of their class, out of their specific social, religious, or cultural confines...they need not be fixed identities; unless you want them to be and seek to preserve them.