KanjiJLPT N3
Seat

squat, seat, cushion, gathering, sit

Mnemonic

Out on the veranda, one person heaps earth into a solid block. A second person plops right down on it — claiming the best seat in the house!
Additional thoughts
Picture two people on a veranda — one building, one sitting. The earth mound sandwiched between two persons forms the inner component (坐), all sheltered under the veranda roof (广).
Quick recall
Two persons on a veranda mold earth into a sturdy seat.

Details

The keyword for 座 is seat. This kanji refers to a place where one sits or a designated spot for sitting, such as a theater seat or a place at a gathering. It extends to mean a constellation (a "seat" in the sky) and can also refer to a gathering or assembly itself. The character conveys the general idea of a fixed position or place one occupies.
On'yomi
Kun'yomi
すわ.る