Мы идём по прямой улице к вокзалу.

Because идём comes from идти, which is the verb of motion used for going in one direction right now.

So Мы идём... means We are going / walking... in a specific direction at this moment.

By contrast, ходим comes from ходить, which is used for:

• repeated or habitual movement,
• movement in different directions,
• general ability or custom.

Compare:

• Мы идём к вокзалу. = We are going to the station now.
• Мы ходим к вокзалу каждый день. = We go to the station every day.

Идём is:

• 1st person plural: we go / we are going
• present tense
• from идти

So the sentence starts with Мы идём... = We are going...

Also, in Russian, the present tense of идти is often translated naturally into English as are going rather than just go, depending on context.

In this sentence, по means something like:

• along
• on
• down a street or path

So по прямой улице means along the straight street.

This is a very common use of по with places you move along:

• идти по улице = to walk along the street
• ехать по дороге = to drive along the road

It does not mean according to here, even though по can mean that in other contexts.

Because по here requires the dative case.

The dictionary form is улица = street.
But after по in this meaning, it changes to the dative singular:

• улица → улице

So:

• по улице = along the street

This is one of the common patterns you need to learn:

• по + dative for movement along a surface, route, or area

Because adjectives have to agree with the noun they describe.

Here, прямой describes улице, so it must match:

• feminine
• singular
• dative

The dictionary form is прямая = straight.
In the sentence it becomes прямой to match улице.

So:

• прямая улица = a straight street
• по прямой улице = along a straight street

Because it is modifying улице.

So по прямой улице is a noun phrase meaning:

• along the straight street

In other contexts, прямой can also mean:

• direct
• straightforward

But here, with улица, the natural meaning is straight.

Because the preposition к takes the dative case.

The dictionary form is вокзал = station.
After к, it becomes:

• вокзал → вокзалу

So:

• к вокзалу = toward the station / to the station

This is a standard rule:

• к + dative

This is a very common question.

• к вокзалу means toward the station or up to the station
• на вокзал means to the station as a destination

In many contexts, both can sound similar in English, but the nuance is different.

к вокзалу focuses more on approaching the station.
на вокзал focuses more on going there as the destination.

So in this sentence, к вокзалу fits the idea of moving along a street toward the station.

Usually, yes: идти is the basic verb for going on foot.

So Мы идём по прямой улице к вокзалу most naturally means:

• We are walking along the straight street toward the station

If you wanted to say we are going by vehicle, Russian would normally use another verb, such as ехать.

Yes, often it can.

Russian verbs already show the person and number, so идём already means we are going.

That means:

• Мы идём по прямой улице к вокзалу.
• Идём по прямой улице к вокзалу.

Both are possible.

Including мы can make the subject clearer or more emphasized. Leaving it out can sound more natural in some contexts.

No, Russian word order is fairly flexible.

The sentence as given is a neutral, natural order:

• Мы идём по прямой улице к вокзалу.

But other orders are possible, depending on emphasis:

• К вокзалу мы идём по прямой улице.
• По прямой улице мы идём к вокзалу.

The basic meaning stays the same because the case endings show the grammatical relationships.

Because Russian has no articles.

So Russian does not have separate words for:

• a / an
• the

Whether you translate something as a street or the street, a station or the station, depends on context.

So:

• по прямой улице could be along a straight street or along the straight street
• к вокзалу could be toward a station or toward the station

The intended meaning comes from context, not from articles.

It is pronounced idyom, because the letter ё is pronounced yo and is always stressed.

So:

• идём = we are going

In many printed texts, Russian writers omit the dots and write е instead of ё, so you may see:

• идем

But in this word, it is still pronounced идём.

The main stresses are:

• мы идём
• по прямо́й у́лице
• к вокза́лу

A useful point:

• ё is always stressed, so идём is easy to stress correctly.

Stress matters in Russian, so it is worth learning words together with their stress.