Left packs selected objects next to each other, aligned on the left. Right packs selected objects next to each other, aligned on the right. The target location for packing Left/Right is the top-most selected object. Top packs selected objects next to each other, aligned on the top. Bottom packs selected objects next to each other, aligned on the bottom. The target location for packing Top/Bottom is the left-most selected object.
The menu shows associated toolbar icons.