gongyeonjang apeseo eungwonbongeul sasseo.

에서 marks the place where an action happens. Since 샀어 means bought, the buying action took place there, so 에서 is natural.

• 공연장 앞에서 = in front of the concert venue / at the front of the venue
• 에 is more often used for location of existence or destination, not the place where an action is carried out.

So:

• 공연장 앞에 있어 = It is in front of the venue
• 공연장 앞에서 샀어 = I bought it in front of the venue

앞 means front.
With particles, it becomes:

• 앞에 = in front of
• 앞에서 = at/in front of (where an action happens)

So 공연장 앞에서 literally means at the front of the concert hall/venue or in front of the venue.

공연장 means performance venue, concert hall, or theater, depending on context.

It is made of:

• 공연 = performance
• 장 = place / venue

So it is literally a place for performances.

응원봉 is a light stick or cheering stick, especially the kind fans use at concerts.

It is made of:

• 응원 = cheering / rooting for
• 봉 = stick / rod

So the word literally suggests a stick used for cheering.

을/를 is the object particle. It marks the thing being acted on.

Here, the verb is 샀어 = bought, so the thing bought is the object:

• 응원봉을 샀어 = bought a light stick

Because 응원봉 ends in a consonant, it takes 을 rather than 를.

• consonant + 을
• vowel + 를

Korean often omits the subject when it is understood from context.

So 공연장 앞에서 응원봉을 샀어 could mean:

• I bought a light stick in front of the venue
• He/She bought a light stick in front of the venue
• We bought a light stick in front of the venue

In many everyday situations, if the speaker is talking about themselves, listeners naturally understand it as I bought.

샀어 comes from the verb 사다, which means to buy.

Conjugation:

• 사다 → 샀어

This is the casual past form, meaning bought.

It may look irregular to learners, but it is just the normal contracted past form of 사다.

Related forms:

• 사요 = buy / buys
• 샀어요 = bought (polite)
• 샀어 = bought (casual)

샀어 is in the casual/informal speech level. It is used with:

• friends
• younger people
• close family members
• people you speak casually with

If you want to say the same thing politely, you would say:

• 공연장 앞에서 응원봉을 샀어요.

So the difference is not in meaning, but in speech level.

Yes. Korean word order is flexible as long as the particles make the roles clear.

This sentence can also be said as:

• 응원봉을 공연장 앞에서 샀어.

Both mean the same thing. The difference is usually just emphasis or natural flow.

Korean often puts the most important or topical information earlier, but the verb normally still comes at the end.

In this sentence, it clearly means the physical location: in front of the venue.

But 앞 can also appear in expressions related to time or sequence in other contexts. Still, with 공연장 앞에서, the natural reading is spatial, not temporal.

So here you should understand it as a real place where the buying happened.

Yes. Korean does not have articles like a and the, so the exact meaning depends on context.

• 응원봉을 샀어 could mean I bought a light stick
• or I bought the light stick

In most out-of-context examples like this, English usually translates it as a light stick unless something specific has already been mentioned.