A particle used in lists like 'A and B and such' (e.g., 'AやらBやら') to indicate several items among others in a vague or casual way.
机の上には書類やら本やらが散らかっている。
Papers, books, and stuff are scattered across the desk.
引っ越しの準備で段ボールやらテープやらを買った。
I bought boxes, tape, and various other things for moving.
疲れていて、ゴミやら洗濯物やらをそのままにしておいた。
I was tired and left things like trash and laundry as they were.
Used to indicate uncertainty or doubt about a state or action (e.g., 'I might go or might not').
彼は行くやら行かないやらはっきりしない。
He's undecided about whether he'll go or not.
値段が高いやら安いやらで意見が分かれた。
Opinions were split about whether it was expensive or cheap.
誰が来るやら分からないから、準備は多めにしておこう。
Since we don't know who might come, let's prepare a little extra.