You will notice there are two ways of saying "what" in Breton: pe and petra.
They're all translated as "what" or "which" in English, but are they are put together with different words.
Pe only goes with a noun:
Pe gador ? Which/What chair?
Petra' only goes with verbs:
Petra emaoc'h o'ch ober ? What are you doing?
Some questions
Petra eo hemañ ? What is this?
Petra eo hennezh ? What is that?
Pe anv oc'h ? What is your name? (lit. What name are you?)