This and that; various things; one thing and another — a vague way to refer to many different items or matters.
旅行の前にあれやこれや準備することがあって忙しい。
I've got various things to prepare before the trip, so I'm busy.
会議ではあれやこれやの意見が出た。
At the meeting, one thing and another were brought up.
部屋の中はあれやこれやで散らかっている。
The room is cluttered with this and that.