This is the 3336th most frequent Dutch word.
it
In Dutch, "it" is not a word.
In this sentence, 'het' refers to the impersonal subject used in weather expressions, common in Dutch.
Het is koud vandaag.
It is cold today.
Here, 'het' is the definite article 'the' referring to the specific object 'book'.
Ik zie het boek op tafel.
I see the book on the table.
In this context, 'het' serves as a pronoun replacing a neuter noun discussed earlier.