Learn Hardcore Korean: jeoneun gonghangeseo bihaenggi pyoreul sayo.

는 is the topic marker. It marks 저 (“I”) as the topic of the sentence—think “as for me.” It sets the context for what follows. If you used 제가, you’d be using the subject marker 가, which emphasizes the doer rather than introducing the topic.

Why do we use 공항에서 instead of 공항에?

에서 indicates the location where an action takes place, so 공항에서 means “at the airport” (the place you buy the ticket).
에 alone would mark a static location (“in/at the airport”) or a destination (“to the airport”) but doesn’t specify “where the action happens.” Saying 공항에 비행기 표를 사요 would sound like “to the airport buy a ticket” and is ungrammatical—you’d need 가서 to express “go and buy.”

What does the 를 in 표를 indicate?

를 is the object marker. It attaches to 표 (“ticket”) to show that it’s the direct object of the verb 사요 (“buy”). Without 를, it wouldn’t be clear what you’re buying.

Why is 비행기 표 ordered that way? Could it be 표 비행기?

In Korean, modifiers come before the noun they modify. 비행기 (“plane”) describes 표 (“ticket”), so you say 비행기 표 = “airplane ticket.” You cannot reverse them.

Why is the verb 사요 at the end of the sentence?

Korean follows Subject-Object-Verb (SOV) word order. All verbs (and adjectives) go at the end of the clause. Hence, 사요 (“buy”) comes last.

What speech level is 사요, and how is it formed?

사요 is the polite informal present tense of the verb 사다 (“to buy”). The stem 사- combines with the polite ending -아요 (used when the verb stem ends in ㅏ or ㅗ). In more formal speech you could say 삽니다 instead.

Can we drop 저는 or 공항에서 in this sentence?

Yes. Korean often omits subjects or locations when they’re understood from context. If it’s clear you’re talking about yourself at the airport, you could simply say 비행기 표를 사요.

Can 비행기 표 be written as one word 비행기표?

Yes. Compound nouns like 비행기표 can be written without a space in Korean. Both 비행기 표 and 비행기표 are correct and mean “airplane ticket.”