This is the 2140th most frequent Catalan word.
apujar
To raise, lift, or increase.
Here, 'apujar' is used to mean 'to increase' or 'to raise' something, specifically the volume.
He d'apujar el volum de la ràdio.
I need to turn up the radio's volume.
In this sentence, 'apujar' is applied to mean 'to raise' a degree or level, such as temperature.
Podem apujar la temperatura del calefactor?
Can we raise the heater's temperature?
Here, 'apujar' is employed in the context of raising or increasing monetary values or prices.