This is the 159th most frequent Polish word.
powodu
"Powodu" means "reason" or "cause" in English.
In this sentence, 'bez powodu' means 'without a reason,' indicating a lack of a specific cause.
Byłem smutny bez powodu.
I was sad without a reason.
Here, 'z jakiego powodu' is a phrase that means 'for what reason,' used to inquire about the cause or reason for something.
Z jakiego powodu spóźniłeś się na spotkanie?
For what reason were you late to the meeting?
Here, 'z powodu' is used to indicate the reason for an action, translated as 'due to' in English.