Learn Hardcore Korean: gageeseo sae begaereul sasseoyo. - I bought a new pillow at the store.

The particle -에서 attaches to a noun to indicate the location where an action occurs. Here, 가게에서 means “at the store.” You use -에서 with action verbs (like buying, eating, studying) to show where the action happens.

Why is there -를 after 베개?

-를 is the object marker, which marks 베개 as the direct object of the verb 샀어요 (“bought”). If a noun ends in a consonant, you use -을; if it ends in a vowel, you use -를. 베개 ends in a vowel, so it takes -를.

Why is 새 placed before 베개, and what’s the difference between 새 and 새로운?

새 is a native Korean adjective meaning “new,” and it directly modifies nouns by being placed in front of them (새 베개 = “new pillow”). 새로운 is the attributive form of the adjective 새롭다 and sounds more formal or literary. In everyday speech, 새 베개 is most common, though 새로운 베개 is also grammatically correct.

What tense and politeness level is 샀어요, and what’s the dictionary form of the verb?

샀어요 is the past-tense polite form (the -요 style) of the verb 사다 (“to buy”). The verb stem is 사-, which becomes 샀- in past tense, and then you add the polite ending -어요 to get 샀어요.

Why is the subject missing? Who is implied?

In Korean, subjects (and other elements) can be dropped when they’re clear from context. Here, it’s understood that I (or we) is the one who bought the pillow. If you wanted to specify I, you could say 저는 가게에서 새 베개를 샀어요.

Can you change the word order, for example 새 베개를 가게에서 샀어요?

Yes. Korean word order is flexible because particles mark grammatical roles. 새 베개를 가게에서 샀어요 is also correct and puts a bit more emphasis on 새 베개. The most neutral order is 가게에서 새 베개를 샀어요, but reordering for emphasis or style is common.

Could you use 가게에 instead of 가게에서, and what’s the difference between -에 and -에서?

-에 indicates a static location (“at” or “in”) or direction (“to”), while -에서 denotes where an action takes place. You’d say 가게에 갔어요 (“went to the store”) with -에 for direction. For “bought,” you need -에서 because it shows the action’s location.

How would you make this sentence more formal or more casual?

More formal (deferential) style:
가게에서 새 베개를 샀습니다.

More casual (informal polite) style:
가게에서 새 베개를 샀어.

Even more casual/blunt (among very close friends):
가게에서 새 베개 샀어.
(Omitting -를 and 요 is common in relaxed speech.)