siheomgwaneun gyocharo-eseo yangboharago malhaessseupnida.

Yes, 시험관 has two common meanings:

• examiner / proctor / test administrator
• test tube

In this sentence, it clearly means examiner, because the person is giving an instruction at an intersection. In context, it is most likely a driving test examiner.

은 is the topic particle.

So 시험관은 means something like:

• as for the examiner
• the examiner, ...

In natural English, you usually just translate it as the subject: the examiner.

Why 은 and not 이?

• 은/는 often marks something already known in the conversation, or adds a slight topic/contrast feeling.
• 이/가 is more purely a subject marker and often sounds more neutral or more focused.

In this sentence, 시험관은 sounds like the examiner is the topic being talked about.

Because 에서 marks the place where an action happens.

Here, the action is 양보하다 (to yield), and that action happens at the intersection, so 교차로에서 is natural.

Compare:

• 학교에서 공부해요 = study at school
• 집에서 먹어요 = eat at home

By contrast, 에 is often used for:

• destination: 학교에 가요 = go to school
• existence/location: 학교에 있어요 = be at school

So in this sentence, 교차로에서 means at the intersection / in the intersection area, where the yielding should happen.

In this sentence, 양보하다 means to yield / give way in a traffic situation.

So it is the kind of yield you do:

• to another car
• to a pedestrian
• to traffic with priority

Outside driving contexts, 양보하다 can also mean things like:

• to уступe / give in
• to concede
• to let someone else have something first

But here it is specifically the traffic meaning: yield the right of way.

양보하라고 uses the pattern:

Verb + (으)라고 하다 / 말하다

This pattern is used for reported commands or instructions, meaning:

• to tell someone to do something
• to say that someone should do something

So:

• 양보하다 = to yield
• stem: 양보하-
• add 라고 → 양보하라고

Then:

• 양보하라고 말했습니다 = said/told someone to yield

A few more examples:

• 가다 → 가라고 했다 = told someone to go
• 먹다 → 먹으라고 했다 = told someone to eat
• 앉다 → 앉으라고 말했다 = told someone to sit down

So 양보하라고 is not just a random quote marker; it is part of a very common grammar pattern for reporting commands.

Because -다고 하다 and -(으)라고 하다 do different jobs.

• -다고 하다 reports a statement
• -(으)라고 하다 reports a command/request

Compare:

• 비가 온다고 말했어요 = said that it is raining
  → statement
• 기다리라고 말했어요 = told someone to wait
  → command

In your sentence, the examiner is not just stating information. The examiner is instructing someone to yield. That is why -(으)라고 is used.

Korean very often leaves out words that are understood from context.

So in this sentence, the person being told is omitted because it is obvious in the situation. If this is a driving-test context, it most likely means the examiner told the test-taker / driver to yield.

If you wanted to make it explicit, you could say something like:

• 시험관은 지원자에게 교차로에서 양보하라고 말했습니다.

Here, 지원자에게 means to the applicant / test-taker.

So the original sentence is perfectly natural even without stating the listener.

Yes. That is a very common alternative.

Both of these work:

• 양보하라고 말했습니다
• 양보하라고 했습니다

Both can mean said/told someone to yield.

The version with 말했습니다 is a bit more explicit because 말하다 literally means to speak / say.
The version with 했다 is extremely common in reported speech and often sounds very natural in everyday Korean.

What you cannot do is use 했습니다 by itself without the reported-command part. The 양보하라고 part is necessary.

말했습니다 is formal polite past tense.

This is the -ㅂ니다 / -습니다 style, which is common in:

• formal speech
• reports
• news
• written narration
• official explanations

Related forms:

• 말했습니다 = formal polite past
• 말했어요 = standard polite past
• 말했다 = plain form / narrative form

So the sentence has a fairly formal, neutral tone.

A possible direct-quote version would be:

• 시험관은 교차로에서 양보하세요라고 말했습니다.

More naturally written, Koreans would usually put quotation marks around the spoken part, but grammatically the key point is that 양보하라고 말했습니다 is the indirect version.

Also, indirect speech does not guarantee the exact original words. The actual words could have been something like:

• 교차로에서 양보하세요
• 교차로에서 양보하십시오
• 교차로에서 양보해요

The sentence only tells you the content of the instruction: the examiner told someone to yield at the intersection.