This is the 13403rd most frequent Polish word.
pachną
"Smell" or "scent" (third-person plural form of "pachnieć," meaning they smell or they emit a scent).
'Pachną' is used as a verb describing the act of emitting a smell, specifically referring to flowers.
Kwiaty w ogrodzie pachną bardzo intensywnie.
The flowers in the garden smell very intensely.
'Pachną' indicates the act of having a particular scent, in this case describing perfumes.
Te perfumy pachną wyjątkowo świeżo.
These perfumes smell exceptionally fresh.
'Pachnie' in this example shows the use of this verb conjugated for 'ciasto' (cake), emphasizing the emitted aroma that's perceived.