What does Ia sakkath Iak sakkakh Ia sha xul mean?

Ia sakkath. Iak sakkakh. Ia sha xul.

If I am not much mistaken, those were the Words found at the bottom of the memorandum from Nightrise Corporation about the Old Ones in the fictional book called Necropolis, by Anthony Horowitz.

scottishbooktrust.com

That is the site for the first chapter of the book where the memo may be read.

It has been said that those Words are of an unknown language.

In google Translate, when asked to detect the language, it mentions that it is Uzbek and that the have no translation for it. Of course this is not entirely reliable.

However, I was able to find a translation on Wikipedia in the article about the book Necropolis, by Anthony Horowitz.

It says: 'It is signed in an unknown language: Ia sakkath. Iak sakkakh. Ia sha xul. Meaning: I call forth the Plumed Serpent of the Deep, Keeper of the Gate!'

Please correct me if this was not what you meant by your question.