Here are the main ways of asking a question.

• Piv (Who) "piu"
• Pe (What) "pe"
• Pelec'h | (Where, literally "What place") "pelex"
• Petra (What, literally "What thing") "petra"
• Pegoulz (When, literally "What period" "peguls"
• Penaos (How) "penaoz"
• Perag (Why, literally "What cause") "perag"

You will notice there are two ways of saying "what" in Breton; pe and petra.
Pe only goes with a noun. And petra only goes with verbs. Petra is really a construction from "pe + tra".

Pe gador? Which/What chair?
Petra emaomp ni o'ch ober? What are we doing?

They're all translated as "what" in English, but are they are put together with different words.

Petra eo hemañ? What is this? (Note: "Is" is a part of the verb "to be")
Petra eo hennezh? What is that?
Pe anv ho peus? What is your name? (lit. What name have you?)
Pe hini? Which one?