Unlike English, which has only one definite article “the", Indonesian has 4 definite articles:

itu (masculine singular), buku itu (the book)

itu (masculine singular) rumah itu (the house)

itu (masculine plural) buku-buku itu (the books)

itu (feminine plural)rumah-rumah itu(the houses)

Indefinite Article:

While we have (a / an / some) in English as indefinite articles, we also have sebuah, beberapa in Indonesian .

In general, whenever (a, an) are used in English you, you need to use (un) or (una) to say the equivalent in Indonesian.

a(masculine singular), sebuah buku(a book)

a (masculine singular) sebuah rumah(a house)

beberapa (masculine plural) beberapa buku (some books)

beberapa(feminine plural) beberapa rumah (some houses)

Example:buku-buku yang saya miliki ada di rumah seorang teman. (The books I have are in a house of a friend)

"Kita" is inclusive; it includes the person that the speaker is talking to. "Kami" is exclusive; it doesn't include the person that the speaker is talking to.

Yes..how do we differintiate A book vs THE book?