Она служила в полиции много лет.

Because the subject is она = she.

In the past tense, Russian verbs agree with the subject in gender and number:

• служил = he served
• служила = she served
• служило = it served
• служили = they served

So Она служила means She served.

Yes, literally it means served, but in this sentence it is often best understood as served in or worked in the police.

The verb служить is commonly used for service in organizations such as:

• the military
• the police
• government structures
• religious service

So Она служила в полиции means something like:

• She served in the police
• She was in the police
• sometimes naturally in English: She worked in the police force

It has a stronger sense of service than the more general verb работать.

Because в here means in, and after в in this meaning, Russian uses the prepositional case.

The noun полиция changes like this:

• dictionary form: полиция
• prepositional singular: в полиции

So:

• в полиции = in the police / in the police force

This is a very common pattern:

• в школе = in school
• в армии = in the army
• в компании = in the company

Because полиция is the basic dictionary form, but after в meaning in, you usually need the prepositional case.

For feminine nouns ending in -ия, the ending often becomes -ии in the prepositional singular:

• полиция → в полиции
• Россия → в России
• академия → в академии

So в полиции is the grammatically correct form.

Много лет is the most common and natural way to say for many years.

A few useful points:

• много = many / a lot of
• лет is the genitive plural form of год or лето? No—here it comes from год / лет in the suppletive plural system used for years.

Russian often uses:

• много лет = many years / for many years
• пять лет = five years
• десять лет = ten years

You can say многие годы, but it sounds more literary or stylistic. In ordinary speech, много лет is much more common.

Because Russian often expresses duration without a preposition.

In English, we say:

• for many years

In Russian, you can simply say:

• много лет

So the duration is understood directly from the expression itself.

Other examples:

• Он жил там три года. = He lived there for three years.
• Мы ждали два часа. = We waited for two hours.

Russian often does not need a separate word for for in time expressions like this.

Служила is imperfective.

The verb pair is:

• служить = imperfective
• a perfective partner is less common in this exact sense and depends on context; for ongoing service, служить is the normal verb

The imperfective is used here because the sentence describes:

• an ongoing activity
• repeated or continuous service
• a period of time: много лет

So Она служила в полиции много лет means she was serving / served in the police over a long stretch of time.

A perfective verb would not fit this meaning as naturally, because the focus here is not on a single completed event, but on the duration of her service.

Usually it means She served in the police for many years.

Because Russian past tense does not directly distinguish between:

• simple past: she served
• past continuous: she was serving

The exact English translation depends on context. But in most cases, the natural translation is:

• She served in the police for many years.

If the surrounding context strongly emphasizes an action in progress, English might use was serving, but the Russian sentence by itself does not force that reading.

Yes, absolutely.

Both are possible, but they are not exactly identical:

• Она работала в полиции = She worked in the police
• Она служила в полиции = She served in the police

Служила sounds more connected to official service, duty, and institutional membership.
Работала is more general and can simply mean she had a job there.

So служила is especially suitable if you want to emphasize that she was an actual serving police officer.

Yes, Russian word order is flexible.

The neutral order here is:

• Она служила в полиции много лет.

But you can also say:

• Она много лет служила в полиции.
• Много лет она служила в полиции.

These all mean basically the same thing, but the emphasis changes a little:

• Она служила в полиции много лет = neutral, matter-of-fact
• Она много лет служила в полиции = emphasizes the long duration a bit more
• Много лет она служила в полиции = strongly foregrounds for many years

Russian word order often reflects emphasis rather than changing the basic meaning.

Yes, literally it is in the police.

Russian often uses в with institutions and organizations where English may use different expressions, such as:

• in the police
• in the army
• in government

So while the literal structure may sound a little different from everyday English, it is completely normal in Russian.

Yes.

Depending on context, много лет can function as:

• a duration: for many years
• sometimes just the time idea many years

In this sentence, it clearly expresses duration:

• Она служила в полиции много лет = She served in the police for many years

Russian often leaves that relationship implicit rather than marking it with a separate preposition.

Then the verb would change to the masculine past form:

• Он служил в полиции много лет.

Compare:

• Она служила = she served
• Он служил = he served

This is one of the most important things to notice about Russian past tense: it shows gender in the singular.