The particle -(이)나 has two very distinct uses that you will need to keep apart. First, you can use the particle to express a choice between two or more options. However, you can also use it that the number of things involved is higher than expected. As you can see, the uses for -(이)나, are very distinct.
The first and most common use for the particle -(이)나 is to create a list of options for someone to pick from. This list can be two or more items long. However, all items need to be nouns for you can only use -(이)나 with nouns. If you want to create a list of choices between actions or states, you will have to use the form -거나.
가: 차나 커피를 마실까요?
나: 커피를 주세요.
A: Do you want to drink tea or coffee?
B: Coffee, please.
Another, less frequent use of -(이)나 is to express that the number of things is greater or higher than what was expected. You can also use it to say that the level of something was higher than you had expected. Because of this when used for this purpose it generally attaches itself to nouns that express a number like counting nouns.
가: 민수 씨는 자동차가 많아요?
나: 네 일곱 대나 있어요.
A: Does Minsu have a lot of cars?
B: Yes, he has as much as seven cars.
How To Use
Like many particles, whether you use -이나 or -나 depends on the final letter of the noun you want to attach it to. If the noun ends in a vowel (no batchim), you use -나. If it does not end in a vowel, but a consonant (batchim), you use -이나.
However, there are a few things you need to keep in mind. The particle -(이)나 oftentimes has t be used with words that already ought to have another particle. Regarding this, there are a few rules to keep in mind:
- If you use -(이)나 with words which either uses the particles -은/는, -이/가 or -을/를, those particles are omitted and replaced with -(이)나.
- For the other particles, like -에, -에서, -에게, you can either use -(이)나 alone or combine it with those particles. In the latter case, -(이)나 is attached to the other particle. Using -(이)나 alone, though, is more natural.