http://ask.yygrammar.com/q-30413.html

It is what lies behind the eerie skills of face-recognition programs and what makes it possible for personal assistants such as smart speakers in the home to pick out spoken requests and act on them. 

参考译文：这就是人脸识别程序诡秘技术背后的原因，也是家用智能喇叭等个人助手能够识别并处理语音请求的原因。

结构解析:两个并列的what 从句都作 is 的表语，同时都在表语从句作主语成分。两个what 都是“融合性关系代词/复合型连接代词”，在本句指“事情的缘由/原因”。

第二个what 从句结构分析：

what （主语）//makes （谓语动词）//it （形式宾语）//possible for personal assistants such as smart speakers in the home（宾补） to pick out spoken requests and act on them（真正宾语）.

短语解析 

(1)pick out：识别

(2)act on：处理