This is the 11442nd most frequent Catalan word.
velat
"Velat" in Catalan means "veiled," "covered," or "obscured."
Here 'velat' is used as an adjective describing the state of the sky, meaning it is covered or obscured by clouds.
El cel és velat per les núvols.
The sky is veiled by clouds.
In this sentence, 'velada' (as the noun related to 'velat') refers to a nighttime gathering characterized as intimate, metaphorically veiled.
La festa era una reunió velada amb intimitat.
The party was a veiled gathering with intimacy.
'Velat' serves to describe the painting as covered by a thin layer, giving the impression of being obscured.