Tell me what it is about .这句话是什么从句?

Tell me what it is about .这句话是什么从句?
Tell me what it is about .这句话是什么从句?

Tell me what it is about .这句话是什么从句?
这是tell somebody something双宾结构,what it is about是直接宾语从句.

定语从句

宾语从句

这是一句宾语从句，what it is about 作tell的双宾语。