This is the 16534th most frequent Polish word.
wiosenną
"Spring" (adjective form: related to spring).
The word 'wiosenną' is used here as an adjective describing the weather ('wiosenna pogoda'). It conveys the sense of 'spring-like' or 'related to spring'.
Lubimy wiosenną pogodę.
We like the spring weather.
Here, 'wiosenną' modifies 'porę' (season), signifying activities associated with the spring period.
Myję okna i sprzątam dom, przygotowując go na wiosenną porę.
I wash windows and clean the house, preparing it for the spring season.
In this sentence, 'wiosenną' qualifies the noun 'roślinność' (vegetation), indicating plants typically connected with or suitable for spring.