te is a definite article
Ko te pukapuka.
The book (singular - only 1 book).
(KO + DEFINITE ARTICLE + NOUN)
Ko te tāne au!
I am the man!
KO + DEFINITE ARTICLE + NOUN + PRONOUN
Ko te wahine au!
I am the woman!
KO + DEFINITE ARTICLE + NOUN + PRONOUN
I haere ia ki te toa.
He went to the shop.
- this is an example of an active sentence