Amandla Stenberg has spent the better part of the last year teaching mainstream culture some serious lessons about race and gender politics. Amanda started with a video on cultural appropriation, came out as bisexual earlier this year, and has now revealed some important information about preferred pronouns. You may be tempted to use "she/her" pronouns when making reference to Amandla, but be aware that "they/them" are actually the preferred ones.
For now, Amandla is has decided to keep their Wikipedia pronouns as "she/her" because "they/them" may affect certain work prospects. The tumblr community can be a lot more understanding when it comes to gender and sex identity than mainstream media. Unfortunately, not everyone could resist giving Amandla a hard time about the revelation.
It's important to realize that Amandla's journey of self-discovery is taking place very much in the public eye. Many celebrities have gone through similar things and chosen to keep that knowledge to themselves. That Amandla is realizing all these things about themself and choosing to share, not hide, is amazing.