This is the 1976th most frequent Turkish word.
parasını
"Parasını" means "his/her/its money" or "the money."
In this sentence, "parasını" means "his money" and is used as the object of the verb "hesaplıyor" which means "calculates."
Ahmet parasını çok dikkatli hesaplıyor.
Ahmet calculates his money very carefully.
Here, "parasını" is again "his money" and is used as the object of the verb "harcamayı" meaning "spending."
Parasını kitaplara harcamayı seviyor.
He likes spending his money on books.
In this example, "parasını" means "his money" and is used as the object of the verb "biriktiriyor" which means "is saving."