This is the 14866th most frequent Polish word.
religii
"Religion" (genitive singular or dative singular form in Polish).
The word 'religii' here is the plural genitive form of 'religia' (religion), used to indicate 'of religions', showing possession or attribution.
Jest wiele religii na świecie.
There are many religions in the world.
'Religii' functions as the plural genitive form after the numeral 'kilku' (a few), indicating 'about religions'.
Znam podstawy kilku religii.
I know the basics of a few religions.
The term 'religii' is in the genitive case, relating to the noun 'historię' (history), specifying what kind of history is being referred to.