Этот район считается безопасным.

Because after verbs like считаться (to be considered) Russian often uses the instrumental case for the noun or adjective that describes what something is considered to be.

So:

• Этот район считается безопасным.
• literally: This district is considered safe.

Here, безопасным is the instrumental singular masculine/neuter form of безопасный.

This is similar to other patterns:

• Он стал врачом. = He became a doctor.
• Она считается умной. = She is considered smart.

So the instrumental here marks the role/quality assigned to the subject.

Считается is the 3rd person singular present form of считаться.

In this sentence, it means:

• is considered
• is regarded as
• sometimes is thought to be

So:

• Этот район считается безопасным.
• = This area is considered safe.

A useful thing to notice is that считаться is related to считать (to count, to consider), but the -ся form often gives a more passive-like meaning:

• считать что-то хорошим = to consider something good
• что-то считается хорошим = something is considered good

In the present tense, Russian usually does not use a verb equivalent to is / are / am.

So English:

• This area is safe
• This area is considered safe

in Russian can be:

• Этот район безопасный. / Этот район безопасен.
• Этот район считается безопасным.

The idea of is is understood from context and sentence structure.

Russian does use forms of быть (to be) in other tenses:

• Этот район был безопасным. = This area was safe.
• Этот район будет безопасным. = This area will be safe.

All of them can sometimes be translated as area or region, but they are not always interchangeable.

• район often means:

  • a district
  • a neighborhood
  • an urban area
  • an administrative district

• регион usually means:

  • a larger region

• область can mean:

  • a province/region
  • also field/domain in other contexts

In Этот район считается безопасным, район most naturally suggests a district or neighborhood.

Yes, but it means something slightly different.

• Этот район безопасный. = This area is safe.
• Этот район считается безопасным. = This area is considered safe.

The second sentence adds the idea of general opinion, reputation, or how people view it.

So:

• безопасный / безопасен = a direct statement
• считается безопасным = a statement about how it is regarded

Both can mean safe, but they are different forms.

• безопасный is the full adjective
• безопасен is the short-form adjective

Examples:

• Этот район безопасный.
• Этот район безопасен.

Both can mean This area is safe, but the short form безопасен often sounds a bit more formal, concise, or statement-like.

In your sentence, though, we do not use either of those forms directly, because after считается we need the instrumental:

• безопасным

Этот means this and agrees with район in:

• gender: masculine
• number: singular
• case: nominative

Because район is masculine singular nominative, we get:

• этот район = this district / this area

Other forms would change depending on the noun:

• эта улица = this street
• это место = this place
• эти районы = these districts

Because район is the subject of the sentence.

The sentence is about what this district is considered to be, so этот район is the thing being described. Subjects are normally in the nominative case.

Structure:

• Этот район = subject, nominative
• считается = verb
• безопасным = predicative complement in the instrumental

Yes, считаться is a -ся verb.

The ending -ся can do several things in Russian, and one of them is to create meanings that are often translated into English with a passive expression.

Compare:

• Люди считают этот район безопасным.

  • People consider this area safe.

• Этот район считается безопасным.

  • This area is considered safe.

So here -ся helps create a meaning like is considered rather than considers itself.

That is important: although -ся is historically related to self, it does not always mean a literal reflexive action.

Yes. Russian word order is flexible, though the most neutral version here is:

• Этот район считается безопасным.

Other orders are possible, depending on emphasis:

• Безопасным считается этот район.
  • emphasis on safe
• Считается безопасным этот район.
  • more marked, less neutral

For a learner, the original order is the best default.

You simply add не before the verb:

• Этот район не считается безопасным.
• = This area is not considered safe.

That means people generally do not regard it as safe.

If you wanted to say directly This area is not safe, that would be different:

• Этот район небезопасен.
• Этот район не безопасный is possible in some contexts, but less standard as a plain statement.

Считается is:

• present tense
• 3rd person singular
• imperfective aspect

The infinitive is считаться.

Why imperfective? Because it expresses a general state/opinion, not a completed one-time action. The sentence means that, in general, the district is considered safe.

You would change the tense of the verb and keep the adjective in the instrumental.

Past:

• Этот район считался безопасным.
• = This area was considered safe.

Future:

• Этот район будет считаться безопасным.
• = This area will be considered safe.

The pattern stays the same:

• subject in nominative
• считаться in the needed tense
• adjective in instrumental

It is fairly neutral and slightly on the formal/informational side.

You might see it in:

• travel advice
• news
• official descriptions
• guidebooks
• discussions of neighborhoods

In casual speech, someone might also say:

• Этот район довольно безопасный.
• Тут безопасно.
• Этот район вроде безопасный.

But считается безопасным is a very normal and useful construction, especially when talking about reputation or general opinion.