This is the 2538th most frequent Catalan word.
caixa
"Caixa" in Catalan means "box" or "cash register."
Here 'caixa' refers to a box, which is the physical object for storage.
He posat la roba dins d'una caixa de cartró.
I've put the clothes inside a cardboard box.
In this context, 'caixa' means the cash register or monetary till of a company.
La caixa de l'empresa es va tancar a les sis de la tarda.
The company's cash register was closed at six in the afternoon.
Here 'caixa' metaphorically represents the source or container of surprises.