This is the 5806th most frequent Russian word.
пятницам
"Пятницам" means "Fridays" (dative plural form).
The word 'пятницам' is used in the dative plural to indicate habitual actions occurring on Fridays.
По пятницам мы ходим в парк.
On Fridays, we go to the park.
Here, 'пятницам' is used in the dative plural to signify the object of dedication in the context of Fridays.
Эти встречи посвящены пятницам.
These meetings are dedicated to Fridays.
In this sentence, 'пятницам' in the dative plural expresses the emotional response towards Fridays.