何を言ってるのか

what someone is saying

→ 何
phrase Uncommon #16,607
what someone is saying 何を言っているのか is the more formal or complete form. Often appears inside a larger sentence, but can also be used on its own in an accusatory way, meaning “what are you saying?”
JA: 彼が何を言ってるのか、よく分かりません。
EN: I don't really understand what he's saying.

何を言ってるのか

What are you talking about?

— きっと、うまくいく (2009)

トム何を言ってるのか聞こえなかったんだ

I couldn't hear what Tom was saying.

何を言ってるのか分かんないよ

I have no idea what you're talking about.

君が何を言ってるのか分からない

I don't understand what you're saying.

— 嵐の中で (2018)

何を言ってるのかさっぱりわからない

I have absolutely no idea what you're talking about.

— レザボア・ドッグス (1992)

お前何を言ってるのかわかってるのか

Do you even realize what you're saying?!

— 紅の豚 (1992)

何を言ってるのかわからないわ

I don't understand what you're saying.

— RRR (2022)

あの人たちが何を言ってるのか分からないけどフランス語だってこと分かります

I don't understand what those people are saying, but I can tell it's French.