The question "What is he going to do?" is commonly used in English to ask about someone's future plans or intentions. It uses the "going to" future tense structure.
The general form for questions with "going to" is:
For third person singular ("he", "she", "it"), we use "is".
We use "going to" to talk about:
❌ What does he going to do? → Incorrect (mixing simple present with "going to")
✅ What is he going to do? → Correct