1An area or vicinity; the surrounding region (used in expressions like "around here").
この辺にコンビニはありますか。
Is there a convenience store around here?
夜になると駅前のこの辺は人通りが少なくなる。
This area in front of the station gets less foot traffic at night.
どの辺にお住まいですか。
Whereabouts do you live?
2In mathematics/geometry: a side or edge of a figure (e.g., a polygon's side or a polyhedron's edge).
三角形の三つの辺の長さを求めてください。
Please find the lengths of the three sides of the triangle.
立方体の各辺は同じ長さである。
All edges of a cube have the same length.
多角形の内角と辺の関係を確認する。
Check the relationship between the interior angles and the sides of the polygon.
3Circumstances or situation; used to refer to the state or particulars of something (often in phrases like "those circumstances").
その辺の事情は私にはよく分からない。
I don't really know the circumstances around that.
その辺の話はまた今度詳しく聞かせてください。
Please tell me more about that some other time.