jeoneun oneul gyeongcharege gyotongsagoreul singohaesseoyo.

저는 is 저 + 는.

• 저 = the humble/polite way to say I
• 는 = the topic marker

So 저는 means something like as for me or speaking of me.

Why not the others?

• 나는 uses 나, which is the plain/casual I. It is not appropriate in a polite sentence ending in -어요 unless the overall speech style is mixed on purpose.
• 제가 uses the subject marker 가. It often sounds more like I as the one who did it, with a bit more focus on the subject.

In this sentence, 저는 is a very natural choice if you are simply talking about what you did today.

Because 오늘 just tells you when the action happened: today.

The verb 신고했어요 is past tense, so the sentence means the reporting happened earlier today.

This works the same way in English:

• Today I reported it
• Today I ate breakfast at 8
• Today I met the police

So there is no contradiction. 오늘 gives the time frame, and 했어요 shows the action is already completed.

경찰에게 means to the police.

The particle -에게 is commonly used for the recipient or target of an action, especially with people or living beings.

In this sentence:

• 교통사고를 = the traffic accident
• 경찰에게 = to the police
• 신고했어요 = reported

So -에게 marks who received the report.

Yes. 경찰에 신고했어요 is also very natural, and many learners will hear that form often.

There is a small nuance:

• 경찰에게 highlights the recipient a bit more
• 경찰에 can feel more like reporting to that authority or institution

With 신고하다, both can appear, and 경찰에 신고하다 is especially common in real life.

So:

• 경찰에게 교통사고를 신고했어요
• 경찰에 교통사고를 신고했어요

Both are understandable and natural.

-를 is the object marker.

It marks 교통사고 as the thing that was reported.

So in this sentence:

• 교통사고를 = the traffic accident, as the direct object
• it answers the question What did you report?

You reported the traffic accident, so -를 is the normal particle here.

It comes from the dictionary form 신고하다, which means to report or to file a report.

This is a 하다 verb:

• 신고 = report/reporting
• 하다 = to do

Then it changes like this:

• 신고하다 → base verb
• 신고했어요 → past tense, polite style

Why 했어요?

Because 하다 in the past polite form becomes 했어요.

You can compare:

• 공부하다 → 공부했어요
• 청소하다 → 청소했어요
• 신고하다 → 신고했어요

So 신고했어요 = reported.

신고했어요 is in the polite informal style, often called the -어요 style.

It is:

• polite enough for everyday conversation
• common in normal speech
• less formal than 신고했습니다

Compare:

• 신고했어 = casual, used with close friends
• 신고했어요 = polite everyday speech
• 신고했습니다 = more formal and official

Since the sentence also uses 저, the overall tone is polite.

Not completely. Korean word order is more flexible than English because particles show each word’s role.

The verb usually stays at the end, but the other parts can move around.

For example, these are all possible:

• 저는 오늘 경찰에게 교통사고를 신고했어요.
• 저는 오늘 교통사고를 경찰에게 신고했어요.
• 오늘 저는 경찰에게 교통사고를 신고했어요.

They all mean basically the same thing, but the emphasis can feel slightly different.

Still, putting 오늘 near the beginning and the verb at the end is very normal.

Yes. Very often, Korean leaves out the subject or topic if it is already clear from context.

So you could simply say:

• 오늘 경찰에게 교통사고를 신고했어요.

That would still sound natural if people already know you are talking about yourself.

Korean often omits words that English usually keeps.

Usually it means the police in a general sense.

Korean often does not mark singular vs. plural unless it matters.

So 경찰에게 here most naturally means to the police as an authority, not necessarily one specific officer.

If you wanted to be more specific, you might say something like:

• 경찰관에게 = to a police officer

But in everyday Korean, 경찰 is very common and natural.

Yes, it is one compound noun:

• 교통 = traffic / transportation
• 사고 = accident

Together, 교통사고 means traffic accident or car accident, depending on context.

Korean often forms words this way by combining two nouns into one compound word.