What exactly is being treated, and why?
Ask which pest has been identified and how, what areas will be treated, and what the treatment is expected to achieve. A vague answer is a reason to ask again.
What are the safety and preparation requirements?
Ask about re-entry times, ventilation, cleaning of surfaces, and precautions for children, pets, or people with allergies or respiratory conditions.
What happens afterwards?
Ask whether a follow-up is likely, what to watch for, and what practical changes will reduce the chance of the problem returning.