noun
movable shelf; whatnot
A small, portable shelf unit that can be placed anywhere, often used for displaying ornaments or storing small items.
部屋の隅に置き棚を置いて、本を並べた。
I put a movable shelf in the corner of the room and lined up books on it.
この置き棚は軽いので、掃除のときに簡単に動かせる。
This movable shelf is light, so I can easily move it when cleaning.
本棚 is a fixed bookshelf, while 置き棚 is a portable shelf that can be moved around.
飾り棚 is a display shelf, often wall-mounted or part of furniture, while 置き棚 emphasizes portability.
Compound of 置き (oki, 'placing', from verb 置く) + 棚 (tana, 'shelf').