This is the 1373rd most frequent Turkish word.
sözlerini
"Their/its words" or "the words of them/it".
Here, 'sözlerini' refers to the words used, functioning as the direct object in relation to the action of 'eleştirmek' ('to criticize').
Konuşmada kullandığı sözlerini eleştirdiler.
They criticized the words he/she used during the speech.
Here, 'sözlerini' means 'his/her words' and is the direct object of the verb 'dinlemek' ('to listen').
Onun sözlerini dinleyerek daha iyi anladım.
I understood better by listening to his words.
In this sentence, 'sözlerini' refers to 'my friend's words' emphasizing the content of speech.