This is the 11801st most frequent Polish word.
korzystną
"Favorable" or "beneficial."
The word 'korzystną' is used here as an adjective meaning 'favorable,' describing the noun 'oferta' (deal), and it is in the accusative case to match the direct object form of the noun.
Kupiliśmy korzystną ofertę na wymarzony wyjazd.
We purchased a favorable deal for a dream trip.
The word 'korzystną' (in its dictionary form 'korzystna') as an adjective is describing the noun 'decyzja' (decision), indicating something beneficial or advantageous.
To była bardzo korzystna decyzja.
It was a very advantageous decision.
The word 'korzystną' (in its dictionary form 'korzystne') is used as an adjective to qualify 'rozwiązania' (solutions), showing that it is beneficial or practical.