bùhǎoyìsi, wǒ lái wǎn le.

不好意思 is a very common polite expression, but it is not exactly the same as 对不起.

In this sentence, 不好意思 means something like:

• Sorry
• Excuse me
• I’m embarrassed / I feel bad

Compared with 对不起, it often sounds:

• softer
• more conversational
• less heavy

So if you arrive late to meet someone, 不好意思，我来晚了。 sounds very natural.

By contrast, 对不起 can sound stronger, more like:

• I’m really sorry
• I’ve wronged you

So both can work, but 不好意思 is often more natural in everyday situations like being late, bothering someone, or asking a small favor.

Chinese often describes situations in a way that sounds more action-based than English.

来晚了 literally breaks down as:

• 来 = come
• 晚 = late
• 了 = indicates a new situation / completed event here

So 我来晚了 is literally something like:

• I came late
• I ended up arriving late

In natural English, we usually say:

• I’m late
• I came late
• I arrived late

Chinese is comfortable using 来 this way when talking about showing up somewhere.

Here, 了 shows that the speaker’s lateness is now an established fact or a new situation.

It does not only mean past tense. Chinese 了 often marks:

• a change of state
• a completed action
• a newly relevant situation

In 我来晚了, it gives the sense:

• I ended up being late
• I arrived late
• So now the situation is that I’m late

Without 了, the sentence would sound incomplete or unnatural in this context.

Yes, 我迟到了 is also very common and often more direct.

Comparison:

• 我来晚了 = I came late / I arrived late
• 我迟到了 = I was late / I arrived late

A small nuance:

• 来晚了 focuses on the fact that your coming/arrival was late.
• 迟到了 uses the set phrase 迟到, which specifically means to be late.

Both are natural. In many real situations, they are interchangeable.

Examples:

• 不好意思，我来晚了。
• 对不起，我迟到了。

Both mean you are apologizing for being late.

These are three different things:

• 晚 = late
• 晚了 = became late / is late now, depending on context
• 晚上 = evening

So in 来晚了:

• 晚 is an adjective meaning late
• 了 belongs to the whole phrase and marks the situation as realized or completed

It is not related to 晚上 (evening).

That is a very common beginner confusion because both use the character 晚.

Because 晚 here is not being used as a simple description like very late. It is part of the result-like expression 来晚了.

Compare:

• 我很晚才来。 = I didn’t come until very late.
• 我来晚了。 = I came late / I’m late.

If you said 我来很晚了, that would not sound right.

So 晚 here is not being modified with 很. It is simply stating that the arrival was late.

Yes. That is very common in spoken Chinese.

Chinese often drops the subject when it is obvious from context. If you are the one speaking after arriving late, everyone already knows the subject is you.

So these are both natural:

• 不好意思，我来晚了。
• 不好意思，来晚了。

The second one sounds a little more casual and conversational.

Yes. This is a good pronunciation question.

The dictionary tones are:

• 不 = fourth tone
• 好 = third tone
• 意 = fourth tone
• 思 = neutral tone or first-tone-like light ending in actual speech, depending on teaching style

But 不 often changes tone before another fourth tone. Since 意 is fourth tone, learners sometimes wonder about tone changes in this phrase.

In practice, 不好意思 is a fixed expression, and the most important thing is to learn its natural rhythm as a chunk:

• bù hǎo yì si

A good learner pronunciation is simply:

• bùhǎoyìsi

Do not over-stress every syllable equally. The phrase usually flows quickly and smoothly.

It is mostly:

• polite
• natural
• everyday
• not too formal

You can use it with:

• friends
• coworkers
• classmates
• a teacher in many situations
• someone you kept waiting briefly

If the situation is more serious or formal, you might choose something stronger, such as:

• 对不起，我迟到了。
• 非常抱歉，我来晚了。

So 不好意思，我来晚了。 is best thought of as a normal, polite everyday apology.

Yes. 来晚了 is the normal way to say came late.

• 来晚了 = arrived late

晚来了 is not the usual neutral phrasing for this meaning. It can sound marked or context-dependent, as if late is modifying the action in a less standard way.

For learners, the safe and natural expression is:

• 我来晚了。

Sometimes context can give it that feeling, but by itself it usually just means:

• I came late
• I’m late

If you specifically want too late, Chinese usually says that more clearly, for example:

• 我来得太晚了。 = I came too late.

So:

• 我来晚了 = late
• 我来得太晚了 = too late

Because 不好意思 works like a separate polite opener, similar to:

• Sorry, ...
• Excuse me, ...

So the sentence naturally breaks into two parts:

1. 不好意思
2. 我来晚了

That pause is very normal in speech too:

• 不好意思， ...
• 我来晚了。

Yes, you may hear 我晚了, but 我来晚了 and 我迟到了 are clearer and more idiomatic in many contexts.

Comparison:

• 我晚了 = I’m late
  
  • short, understandable, but less specific
• 我来晚了 = I came late / I arrived late
• 我迟到了 = I was late / I arrived late

For a learner, the most natural full sentences are:

• 不好意思，我来晚了。
• 不好意思，我迟到了。

In basic vocabulary, 来 means come, usually toward the speaker or toward the reference point.

But in real Chinese, 来 is also used more broadly for arrive / come over / show up, depending on context.

So in 我来晚了, it does not have to mean you are physically moving toward the person speaking. It can simply mean:

• I showed up late
• I arrived late

This is one reason why translating word-for-word can feel strange. It is better to understand 来晚了 as a natural chunk meaning arrived late.