وَمَا كَانَ عَوْرَةً مِنَ الرَّجُلِ فَهُوَ عَوْرَةٌ مِنَ الْأَمَةِ، وَبَطْنُهَا وَظَهْرُهَا عَوْرَةٌ، وَمَا سِوَى ذَلِكَ مِنْ بَدَنِهَا لَيْسَ بِعَوْرَةٍ
Translation: Whatever is awrah for a man is also awrah for a female slave; additionally her abdomen and back are awrah, whereas the remaining portions of her body are not.
Amah is the historical juristic term for a female slave, reflecting the former legal system of slavery. These historical categories are not interchangeable with the rulings for free women today.
For this historical category, the text adds the abdomen and back to the male awrah boundaries.