This translation "I eat the apple" should also work. As Indonesian is not as strict as English is about articles.
"Saya makan apel" could mean "I eat an apple", "I eat the apple", "I eat the apples", or "I eat apples". Depending on the context.
If you want to be very explicit, and mean only "I eat the apple", you can say "Saya makan apel itu", but it can also be translated with I eat that apple".
And you can also say "Saya makan apelnya", but it can also be translated with "his apple", or "her apple", (and "their).
for more detailed explanation please refer to PERCE_NEIGE's comment as he/she elaborate the concept very clear even more clearer that I, a native speaker, can. lol. Good job PERCE_NEIGE!
so first thing first, Bahasa Indonesia doesn't really put much emphasize on the articles (well at least IMO), so definite and indefinite articles is rarely used in everyday conversation, UNLESS it is necessary to do so. for example let's say you're most favorite/beloved fruit is APPLE, and you want to say that out loud: is it really important to emphasize singular/plural form of the word "apple" here? you love the fruit anyway, right? that's probably how it goes in the mind of many Indonesians (or at least just me). that's why: I like apples! is translated to "Saya suka apel!" and not "Saya suka apel-apel!", here the plural forms is implied, you can understand it from the context that this person like APPLES not just AN APPLE.
So another example for you, let's say you're so busy that evening that you skipped lunch and had only AN apple for lunch, and your friend is asking you:
Friend (F): what do you have for lunch? (Ind: apa yang kamu makan untuk makan siang? or most likely and less awkwardly most Indonesians will say this: "makan apa kamu tadi?")
You (Y): an apple. (Ind: apel.)
F: only an apple? is that enough? (Ind: hanya sebuah apel? apakah itu cukup?) ........
you see from the example above that in Indonesian, you actually could say "apel" without any articles (be it "an" [Ind: sebuah] or "the"). if that conversation really happened in Bahasa Indonesia your friend probably would ask you first: "how many apples do you have for lunch? (Ind: berapa banyak?)" just to make sure, and only after that he/she will reply in awe: "is it enough?".
That's probably why I find it so difficult to grasp the basic concept of French because in Indonesia we can say "jeruk" (Ind. for orange [fruit]) while in French you have either "l'orange" or "une orange" right?
Probably the same reason why many Indonesians who just started learning English, usually forget to put "a" or "an" where it should be..
Hope this lingobabble can answer your question.
Just a precision: In this language, there are 2 forms of plural, the explicit plural, and the implicit one.
Apel-apel is the explicit plural, as it only mean appleS. But apel could be used to mean a plural also (implicit plural)
So apel could be apples or apple, depending on the context, unless you have an explicit singular, like "sebuah apel" = an apple.
Although in Indonesian a word can be pluralized by repeating it (with a hyphen in between), it's not always necessary. "Apel" can be singular or plural, and you can determine this from the context.
The store sells apples.
Toko itu menjual apel. (It would be weird to say "Toko itu menjual apel-apel.")
Yes, but "I eat an appel" can be translated with "Saya makan apel". See novels translation, and you will meet that all the time.
"Saya makan sebuah apel" is only used when you want to be unambiguous, because you don't want any ambiguity. In other cases, they won't use the "sebuah".
Yes, and there are several other "a/an", depending what you are counting.
Sebuah is for object, for instance fruit.
Sebuah apel dan sebuah pisang (an apple and a banana).
Seorang is for people.
Seorang pria dans seorang wanita (a man and a woman)
Seekor is for animal.
Seekor anjing dan seekor kucing (a dog and a cat)
Secangkir is for drink, in cups.
Secangkir kopi (a cup of coffee).