tikadou kara tizyou ni deru to, eki mae no hiroba ga miemasu.

Here, から marks the starting point of movement: from the underpass / from the underground passage.

So:

• 地下道から = from the underpass
• 地上に出る = go out onto the ground / emerge to street level

This is different from から meaning because. Japanese から has multiple uses, and this is the location/source use.

With 出る, the particle often depends on what part of the movement you want to highlight:

• X を 出る = leave X
• Y に 出る = come out to Y / emerge into Y

In this sentence:

• 地下道から gives the place you are coming from
• 地上に gives the place you are emerging to

So the structure is basically:

from the underpass → out to ground level

That is why に is natural with 地上 here.

In this sentence, と means something like:

• when
• once
• as soon as

It connects two events in a natural sequence:

• 地下道から地上に出ると
• when you come out from the underpass to ground level...

This と is often used when one thing automatically or naturally happens after another. It can sound like: if/when X happens, Y is what you see / what happens next.

Because in grammar patterns like this, Japanese normally uses the plain form before と.

So:

• 出る
  • と = correct
• 出ます
  • と = generally not used in normal modern speech for this grammar pattern

Even though the sentence ends politely with 見えます, the verb before と stays in plain form. This is very common in Japanese:

• 春になると、暖かくなります。
• 右に曲がると、銀行があります。

So the politeness of the whole sentence does not mean every verb inside it becomes polite.

駅前 means the area in front of the station.

It is a very common compound word:

• 駅 = station
• 前 = front
• 駅前 = in front of the station / station-front area

This often refers not just to the exact spot directly before the station entrance, but the general area around the station frontage.

So 駅前の広場 means the plaza in front of the station or the station-front plaza.

Because 駅前 is modifying 広場.

• 駅前 = station-front area
• 広場 = plaza
• 駅前の広場 = the plaza in front of the station

The particle の connects nouns, similar to of or a noun modifier in English. It tells us what kind of plaza it is.

You can think of it as:

• 駅前の広場 = the station-front plaza

This is one of the most important points in the sentence.

見える and 見る are different verbs:

• 見る = to look at / to watch
• 見える = to be visible / to come into view / can be seen

Here the sentence is not emphasizing that someone actively looks at the plaza. Instead, it says that the plaza becomes visible.

So:

• 広場を見ます = someone looks at the plaza
• 広場が見えます = the plaza is visible / you can see the plaza

That is why が is used with 見える. The thing that is visible is marked by が.

Not exactly.

見える is usually treated as its own verb, meaning:

• is visible
• can be seen

It overlaps in meaning with English can see, but grammatically it is not just the regular potential form of 見る.

Compare:

• 見る → to look at
• 見える → to be visible
• 見られる → can see / be able to see (potential of 見る)

In many real situations, 見える is the most natural choice when something simply comes into view.

So in this sentence, 見えます suggests: when you come out onto ground level, the station-front plaza comes into view / is visible.

Japanese often leaves out subjects when they are understood from context.

In this sentence, the omitted subject could be something like:

• you
• I
• one
• people

depending on the situation.

So the sentence is not focused on who comes out of the underpass. It focuses on what happens when someone does:

When (you/one/I) come out from the underpass to ground level, the plaza in front of the station becomes visible.

This kind of omission is extremely normal in Japanese.

Japanese non-past forms often cover both present and future, and they can also describe general truths or habitual results.

Here, 見えます does not necessarily mean only you are seeing it right now. It can mean:

• you will see it
• you can see it
• it comes into view
• that is what happens when you come out there

So the sentence has a general, descriptive feel: When you come out from the underpass to street level, the station-front plaza is visible.

Yes, in many situations たら could be used, but the nuance changes a little.

• 出ると often sounds like a natural/automatic result
• 出たら often sounds more like when/after in a particular situation

So:

• 地下道から地上に出ると、駅前の広場が見えます。 = When you come out, the plaza comes into view.
  (natural result / what you find there)

• 地下道から地上に出たら、駅前の広場が見えます。 = When/after you come out, you can see the plaza.
  (also possible, a bit more event-based)

In this sentence, と is very natural because it describes what you see as the normal result of coming out of the underpass.

No. 地下道 means an underground passage, underpass, or pedestrian tunnel.

It is made of:

• 地下 = underground
• 道 = road/path/way

So this is not the subway railway system. For that, Japanese would more often use words like:

• 地下鉄 = subway / metro
• 駅 = station

Here, 地下道 is the passage you walk through underground, then come out of to reach the surface.

The comma is mainly there to make the sentence easier to read and to show a pause:

地下道から地上に出ると、駅前の広場が見えます。

It separates the when-clause from the main statement. In many cases, the sentence could be written without the comma, especially in short text, but using it here is very natural and helpful.

It does not change the basic grammar.