saisyuu densya ha mou deta.

It is read:

さいしゅう でんしゃ は もう でた。

If written without the learner-style spaces, it is:

最終電車はもう出た。

A natural English gloss is The last train has already left.

Japanese normally does not use spaces between words, so the standard writing is:

最終電車はもう出た。

The spaces here are just for learners, to make the parts easier to see:

• 最終電車 = last train / final train
• は = topic marker
• もう = already
• 出た = left / departed

So the spaced version is a teaching aid, not normal everyday spelling.

最終電車 literally means final train or last train.

• 最終 = final, last
• 電車 = train

In natural English, last train is usually the best translation.

Also, in everyday Japanese, people very often say 終電（しゅうでん） instead of 最終電車.
So:

• 最終電車 = a bit fuller / more formal
• 終電 = very common in daily conversation

は marks the topic of the sentence.

So 最終電車は means something like:

As for the last train, ...

Then the sentence comments on that topic:

...it has already left.

English usually does not mark topics this way, so this can feel strange at first. But in Japanese, は is extremely common when introducing what the sentence is about.

Using は here presents the last train as the topic, something already understood or relevant in the conversation.

最終電車はもう出た。
= As for the last train, it’s already left.

If you used が, it would sound more like identifying or emphasizing the subject:

最終電車がもう出た。

That is not impossible, but it feels less neutral in many contexts. は is more natural if you are simply informing someone about the status of the last train.

A rough contrast:

• は = talking about it as the topic
• が = highlighting it as the subject, often with stronger focus

Here, もう means already.

So it shows that the action has happened by now, possibly earlier than someone expected.

In this sentence:

もう出た = has already left

This is a very common use of もう with past tense.

Be careful, because もう can also mean more / another in other sentences, such as:

• もう一回 = one more time
• もう一つ = one more

So the meaning of もう depends on context.

Yes, 出る often means to go out, to come out, or to leave. But with transportation, it can also mean to depart.

So for trains, buses, and similar things:

• 電車が出る = the train leaves / departs
• バスが出る = the bus leaves / departs

In this sentence, 出た is the past tense of 出る, so it means:

left / departed

This is a very common usage in Japanese.

Japanese past tense often covers both a simple past idea and what English expresses with the present perfect.

So 出た can correspond to:

• left
• has left

In this sentence, because of もう, the natural English translation is often:

has already left

Japanese does not have a separate verb form that works exactly like the English present perfect, so the plain past form often does that job.

Yes, possibly. Japanese often leaves out information that is obvious from context.

For example, the sentence does not explicitly say:

• where the train left from
• who is talking
• why this matters

It simply says that the last train has already departed.

Depending on context, English might make some of that explicit, but Japanese does not need to. This kind of omission is completely normal.

Yes, very easily.

Because it says もう出た — it’s already left — it often implies something like:

• You missed it.
• We can’t catch it now.
• That option is gone.

The sentence itself is neutral grammar-wise, but in real conversation it often carries that practical implication.

It is correct, but in everyday speech, 終電（しゅうでん） is often more natural and common.

So a very common conversational version would be:

終電はもう出た。

That means the same thing: The last train has already left.

So you should recognize both:

• 最終電車 = full expression, clear, somewhat more formal
• 終電 = shorter, very common in real life