This is the 256th most frequent Catalan word.
fills
"Fills" means "sons" or "children" in English.
In this sentence, 'fills' is used as a noun meaning 'children,' referring to the offspring of someone.
Els fills d'en Joan són molt amables.
Joan's children are very kind.
Here, 'fills' is a conjugation of the verb 'omplir,' meaning 'to fill,' used in the third person singular present tense.
Ell fills la tassa de cafè cada matí.
He fills the coffee mug every morning.
In this instance, 'fills' metaphorically describes the streams as being 'full' (of energy), indicating an attribute.