Мэр работает в городе.

• мэр is the subject: the person doing the action.
• работает is the verb: it tells you what the subject does.
• в городе is a prepositional phrase: it tells you the location.

So the structure is:

subject + verb + location

This is a very normal, neutral Russian sentence pattern.

Because в городе expresses location: the mayor works in the city.

After в, Russian uses different cases depending on the meaning:

• в городе = in the city / located there
• в город = into the city / movement toward it

So:

• Мэр работает в городе. = location
• Мэр едет в город. = movement

That is why город changes to городе here.

It is the prepositional case singular.

The base form is город.
After в when you mean in/at a place, Russian often uses the prepositional case:

• город → в городе
• банк → в банке
• парке → в парке

So the ending -е is a normal prepositional singular ending for many masculine nouns.

Работает is:

• present tense
• 3rd person singular
• from the verb работать (to work)

So it matches a singular subject such as мэр.

You can think of it as the form used with:

• он работает
• она работает
• мэр работает

In the present tense, Russian verbs do not show gender, so работает can go with either a male or female subject.

Yes.

Russian present-tense forms often cover both ideas:

• habitual: works
• right now: is working

So работает can mean either:

• the mayor works there in general
• the mayor is working there now

The broader context tells you which one is intended.

Because Russian has no articles.

English uses:

• a mayor
• the mayor
• a city
• the city

Russian usually just says:

• мэр
• город

Context tells you whether the meaning is more like a or the.

So Мэр работает в городе. can be interpreted naturally from context without needing articles.

Because the subject noun мэр is already stated.

Russian does not need to add он if the subject is already clear. In fact, adding it here would usually sound unnecessary.

Natural:

• Мэр работает в городе.

Less natural in this context:

• Мэр, он работает в городе.

If you remove the noun, then a pronoun can be used:

• Он работает в городе.

Yes. Russian word order is more flexible than English because case endings help show the grammatical relationships.

The most neutral order here is:

• Мэр работает в городе.

But other orders are possible for emphasis:

• В городе работает мэр.
  Focuses more on in the city
• Работает мэр в городе.
  Possible, but more marked or stylistic

So the original sentence is the most straightforward, textbook order.

The stress is:

• мэр
• рабо́тает
• в го́роде

A helpful learner-friendly pronunciation guide is:

• мэр ≈ mer
• рабо́тает ≈ ra-BO-ta-yet
• в го́роде ≈ v GO-rə-dye

Two useful notes:

1. мэр uses the letter э, which clearly gives an e sound like in bed.
2. Unstressed о in Russian is usually reduced in pronunciation, so it does not sound like a full English o.

Мэр is in the nominative case because it is the subject of the sentence.

The nominative is the dictionary form and is typically used for the person or thing doing the action.

Here:

• мэр = the one who works
• работает agrees with that subject in number and person

So мэр is simply the normal subject form.

Grammatically, мэр is a masculine noun.

Traditionally, Russian often uses мэр for the office itself regardless of the person’s sex. If the mayor is a woman, Russian may still use мэр, though surrounding words can vary depending on style and modern usage.

In this sentence, the present-tense verb работает does not show gender, so the sentence itself does not make that distinction through the verb.