This is the 621st most frequent Turkish word.
istediğini
"The thing that (someone) wants."
In this sentence, 'istediğini' implies 'what he wants' and represents the object of 'alabilir' (can take).
Ahmet istediğini alabilir.
Ahmet can take what he wants.
Here, 'istediğini' means 'what you want' and acts as the object of 'söylemekten' (from saying).
İstediğini söylemekten çekinme.
Don't hesitate to say what you want.
In this sentence, 'istediğini' refers to 'what you wanted' and indicates the direct object of 'hazırladım' (prepared).