This is the 207th most frequent Turkish word.
hızlı
"Fast" or "quick."
Here, 'hızlı' is used metaphorically to describe the abstract noun 'karar vermek' (decision-making), implying hastiness or rapidity in the process.
Hızlı karar vermek bazen yanlış sonuçlara yol açabilir.
Making decisions quickly can sometimes lead to wrong outcomes.
Here, 'hızlı' is used as an adjective to describe the noun 'tren' (train), indicating that the train is fast.
Hızlı bir tren seyahati yaptık.
We took a fast train journey.
In this sentence, 'hızlı' is used as an adverb, modifying the verb 'koştu' (ran), to indicate the speed at which the action was performed.