What is the Greek word for he?

The Greek word for "he" depends on the case. There isn't one single word. The most common forms are:

* Nominative: αὐτός (autos) - This is used for the subject of a sentence. "He did it."

* Accusative: αὐτόν (auton) - This is used for the direct object. "I saw him."

* Genitive: αὐτοῦ (autou) - This shows possession. "His book."

* Dative: αὐτῷ (autōi) - This is used for the indirect object. "I gave it to him."

So there's no single answer, you need to know the grammatical function of "he" in the sentence.