A casual way to ask roughly where (or when/around what point) something is; asks for approximate location, time, or range.
駅のどこらへんに待ち合わせようか？
Where around the station shall we meet?
その店は市役所のどこらへんにありますか？
Around where is that shop in relation to the city hall?
旅行は来月のどこらへんを予定していますか？
Around when next month are you planning the trip?
その問題はどこらへんから始まったのか詳しく教えてください。
Please tell me in detail roughly where that problem started.