This is the 4923rd most frequent Polish word.
piszą
"Piszą" means "they write."
In this sentence, 'piszą' is used as the present tense form for the third-person plural of the verb 'pisać' which means 'to write.'
Dzieci piszą listy do Świętego Mikołaja.
The children are writing letters to Santa Claus.
Here, 'piszą' indicates a habitual action in the present tense related to creating written works.
Piszą artykuły dla lokalnej gazety.
They write articles for the local newspaper.
In this example, 'piszą' refers to simultaneous writing by multiple individuals at the current moment.