This character does not have any inherit meaning per se, but is instead used simply to transliterate the 'sa' sound.
Mnemonic
[s-] Spongebob is in the [4] bathroom of the [-a] auditorium where he has been hired to decorate it. He sits on top of a 文 giant as he paints 阝 hills of 艹 flowers onto the wall, and on those 阝 hills many different colorful 生 aliens and a huge 厂 cliff. The bathroom attendants look on impatiently while rubbing their fancy dress shoes on the tile floor making a 薩 sa薩 sa sound. Spongebob continues to paint as he and the 文 giant sing a tune: "薩 sa薩 sa薩 sa...". His mural he has named the "薩 Sa Mural".