Судья назначил пенальти, и болельщики на трибуне громко закричали.

Because судья is one of those Russian nouns that can refer to a male or female person, even though its form looks like a typical feminine noun.

In this sentence, we know it is masculine because the past-tense verb is назначил, not назначила.

• судья назначил = the judge/referee awarded... (male)
• судья назначила = the judge/referee awarded... (female)

So the noun itself stays судья, but the verb shows the person’s gender in the past tense.

Literally, назначить often means to appoint, to assign, or to designate. But in sports Russian, назначить пенальти is a standard expression meaning:

• to award a penalty
• to give a penalty kick

So here судья назначил пенальти means the referee decided that a penalty should be taken.

This is a good example of a verb whose basic meaning expands in context. In sports, назначить is very natural with things like:

• назначить штрафной = award a free kick
• назначить пенальти = award a penalty

It is functioning as the direct object, so yes, logically it is in the accusative. The reason it does not visibly change is that пенальти is an indeclinable borrowed noun.

That means the form stays the same in all cases:

• nominative: пенальти
• accusative: пенальти
• prepositional: о пенальти
• etc.

Many loanwords in Russian behave this way.

So in назначил пенальти, the word is the object of the verb, but its form remains пенальти.

Болельщики is the nominative plural form of болельщик (fan, supporter).

It is in the nominative because it is the subject of the second clause:

• болельщики ... закричали = the fans shouted

Singular and plural:

• болельщик = fan
• болельщики = fans

The verb also matches this plural subject:

• закричал = shouted / cried out (singular masculine)
• закричали = shouted / cried out (plural)

На трибуне is prepositional case after на, because it expresses location:

• на трибуне = in the stands / on the stand / in the bleachers

Russian commonly uses:

• на + prepositional for location
• на + accusative for motion toward something

Compare:

• болельщики на трибуне = the fans in the stands
• болельщики пошли на трибуну = the fans went to the stands

So here there is no movement; it just tells us where the fans were.

Because громко is an adverb, and it modifies the verb закричали.

It tells us how they shouted:

• громко закричали = shouted loudly

An adjective would modify a noun, not a verb. For example:

• громкий крик = a loud cry
• громкие болельщики = loud/noisy fans

But here we are describing the action, so Russian uses the adverb:

• громко

This is a very important aspect question.

• закричали is perfective
• кричали is imperfective

In this sentence, закричали means something like:

• cried out
• started shouting
• shouted

It presents the shouting as a single event that began after the referee awarded the penalty.

The prefix за- often gives the idea of beginning an action:

• кричать = to shout, to be shouting
• закричать = to start shouting / to cry out

So:

• болельщики громко закричали = the fans suddenly loudly shouted / cried out
• болельщики громко кричали = the fans were shouting loudly

The sentence uses закричали because it fits the sequence of events well: first the referee awarded the penalty, then the fans burst into shouting.

Because the sentence contains two separate clauses, each with its own subject and verb:

1. Судья назначил пенальти
2. болельщики на трибуне громко закричали

Since these are two independent clauses joined by и (and), Russian normally puts a comma before и.

So the comma works much like in English when two full clauses are joined:

• The referee awarded a penalty, and the fans in the stands shouted loudly.

If the parts did not form separate full clauses, there might be no comma, but here they clearly do.

The word order can be changed, because Russian word order is fairly flexible. But the given version is neutral and natural.

Current order:

• Судья назначил пенальти, и болельщики на трибуне громко закричали.

This presents the events clearly and straightforwardly.

Other possible orders might be:

• Судья назначил пенальти, и на трибуне болельщики громко закричали.
• Болельщики на трибуне громко закричали, когда судья назначил пенальти.

These are possible, but they may shift the emphasis slightly.

In the original sentence:

• болельщики is highlighted first as the subject
• на трибуне simply adds location
• громко naturally comes before the verb or near it

So the original word order is a good standard model for learners.

In general Russian, судья can mean either:

• judge in a legal sense
• referee/official in sports

Here the context makes it clearly a sports referee, because of назначил пенальти. A courtroom judge would not award a penalty kick.

So in this sentence, the best translation is referee.