eki no mae wo toorisugiru to, hidari ni tosyokan ga arimasu.

In this sentence, を marks the place that someone moves through or past.

So 駅の前を通り過ぎる means something like:

• to pass by the area in front of the station
• to go past the front of the station

This is a common use of を with movement verbs:

• 道を歩く = walk along the road
• 公園を散歩する = stroll through the park
• 空を飛ぶ = fly through the sky

So here, 駅の前 is the space being passed through/past, not just a static location.

駅の前 literally means the front of the station or the area in front of the station.

Breakdown:

• 駅 = station
• の = links nouns, like of
• 前 = front / before

So 駅の前 = the station’s front → more naturally, in front of the station.

In this sentence, it refers to the area by the front of the station that you pass.

通り過ぎる means to go past, to pass by, or sometimes to pass beyond.

It is built from:

• 通る = to pass through / go along / pass
• 過ぎる = to exceed / go past

So 通り過ぎる feels stronger than 通る. It emphasizes going past something.

Compare:

• 駅の前を通る = go through/past the front of the station
• 駅の前を通り過ぎる = pass right by the front of the station

In this sentence, 通り過ぎる fits well because it sounds like giving directions based on moving past a landmark.

No. This と is not the and/with particle.

Here, と means when or if, in the sense of a natural result:

• 駅の前を通り過ぎると、左に図書館があります。
• When you pass the front of the station, there is a library on the left.

This と is often used when:

• one thing regularly leads to another
• the result is automatic or expected
• you are describing directions, instructions, or general facts

So it has a very natural when you do X, you find Y feeling.

Because Japanese commonly uses the plain non-past form before と.

So even if the meaning is future in English, Japanese still uses:

• 通り過ぎると = when you pass
• not a special future form

Japanese does not have a separate future conjugation like English does. The non-past form can mean:

• present
• future
• habitual/general action

Here it gives a general directional meaning: when you pass there, this is what you’ll see.

Because に is used in existence sentences to mark where something is.

The basic pattern is:

• place に thing が あります

So:

• 左に図書館があります
• There is a library on the left.

Here, 左に means on the left or to the left.

Using で would not fit this structure, because で usually marks the place where an action happens, not where something exists.

Compare:

• 公園にベンチがあります。 = There is a bench in the park.
• 公園で遊びます。 = I play in the park.

Because in an existence sentence, the thing that exists is often marked by が.

Pattern:

• place に thing が あります / います

So here:

• 左に = location
• 図書館が = the thing that exists
• あります = exists / there is

That gives:

• On the left, there is a library.

You could sometimes use は instead, but that would change the nuance. が is the normal choice when introducing or pointing out something that is there.

Because あります is used to say that something exists or is located somewhere.

• 図書館があります = There is a library.
• 図書館です = It is a library.

So あります is the right choice when giving directions and pointing out what is somewhere.

Also, あります is used for inanimate things, and a library counts as inanimate.

If it were a person or animal, you would use います instead:

• 左に先生がいます。 = There is a teacher on the left.

Yes, the subject is omitted.

Japanese often leaves out the subject when it is obvious from context. In a directions sentence like this, the hidden subject is usually something like:

• you
• one
• the person going that way

So the sentence naturally means:

• When you pass the front of the station, there is a library on the left.

Even though you is not stated, it is understood.

Yes, たら is possible:

• 駅の前を通り過ぎたら、左に図書館があります。

This would also mean something like when/after you pass the station front, there is a library on the left.

The difference is nuance:

• と sounds more like a general, automatic result or standard directional description
• たら sounds a bit more like once you do that, then...

For directions and map-style explanations, と is very natural because it presents the next thing as what you naturally encounter.

Yes. A few natural alternatives are:

• 左側に図書館があります。
  More explicit: There is a library on the left side.

• 左手に図書館があります。
  Very common in directions: There is a library on your left.

• 左にあるのが図書館です。
  More like: The one on the left is the library.

Your original sentence is perfectly natural, but 左手に is especially common when guiding someone along a route.