This is the 2403rd most frequent Catalan word.
posar
"Posar" means "to put" or "to place" in English.
Here, 'posar' means 'to set', as in arranging or preparing an object or area.
He de posar la taula abans del sopar.
I need to set the table before dinner.
In this context, 'posar' means 'to put on', referring to clothing or attire.
Cada vegada que plou, s'ha de posar l'impermeable.
Every time it rains, one should put on the raincoat.
In this usage, 'posar-se' is reflexive and means 'to set', as in describing the sunset.