This is the 28th most frequent Hungarian word.
ez
"This."
The word 'ez' is used here as a demonstrative pronoun indicating 'this' referring to 'this day'.
Ez egy szép nap.
This is a beautiful day.
The word 'ez' is used as a demonstrative adjective modifying 'car'.
Ez az autó gyors.
This car is fast.
The word 'ez' is used as a pronoun representing 'this' in a general context.