* Unlike English, Indonesian nouns do not have an “s” added to indicate pluralization. Itu buku can mean “It is a book” or “those are books”.
* Apa itu? Has a similar meaning to Itu apa?, but Itu apakah? Is not used. Also, Apa itu? And apakah itu? Have a similar meaning. The particle -kah is combined with the interrogative apa to create a question. However, a question can be commonly asked without using this particle.
Apa itu pensil? → Itu pensil? Is that a pencil?
If apakah is used, more emphasis is on the question.
Apakah itu pensil? → Itu pensil? Is that a pencil?
The interrogative apakah is usually used to introduce “yes-no” questions and is placed at the beginning of a question when the answer is ya or bukan/tidak.
Apakah ini baju? Is it a shirt?
(+) Ya, ini baju. Yes, it is a shirt.
(-) Bukan, ini bukan baju. No, it is not a shirt.