Болельщики на трибуне спорили, почему получилась ничья.

Болельщики is the nominative plural form, because it is the subject of the sentence.

• singular: болельщик = a fan, supporter
• plural: болельщики = fans, supporters

This word usually means people who support a team, especially in sports.

In stadium contexts, трибуна means the stand, grandstand, or seating section for spectators. Russian normally uses на with this word:

• на трибуне = in the stands / on the stand

Even though English says in the stands, Russian uses на. This is just the normal idiomatic choice.

Also, трибуне is the prepositional singular form of трибуна, used after на when talking about location.

It is the prepositional case singular.

The base form is:

• трибуна

After на when it means at/on/in a place, Russian usually uses the prepositional case:

• на трибуне

So the ending changes from -а to -е.

Спорили is:

• past tense
• plural
• imperfective

It is plural because the subject is болельщики.

It is past tense because the action happened in the past.

It is imperfective because it describes an ongoing or repeated action in the past: the fans were arguing / were debating, not just a single completed moment of argument.

The infinitive is спорить.

Спорить can mean anything from argue to debate to dispute. In this sentence, it most likely means they were arguing about the reason for the draw.

So it does not have to mean a dramatic fight. It can simply mean they disagreed and were discussing it actively.

Because почему получилась ничья is a subordinate clause.

The main clause is:

• Болельщики на трибуне спорили
  The fans in the stands were arguing

The subordinate clause explains what they were arguing about:

• почему получилась ничья
  why it ended in a draw / why a draw happened

Russian normally separates this kind of subordinate clause with a comma.

This is a very natural Russian way to express the result of something.

• была ничья = there was a draw
• получилась ничья = it turned out to be a draw / the result was a draw

The verb получиться often has the sense of turn out, come out, or end up as. Here it emphasizes the outcome of the match.

So получилась ничья sounds a bit more like talking about how the game ended up.

Because it agrees with ничья, which is a feminine singular noun.

• ничья = draw, tie
• therefore: получилась

Russian past tense verbs agree in gender and number when the subject is singular:

• masculine: получился
• feminine: получилась
• neuter: получилось
• plural: получились

Here, ничья is the grammatical subject of the subordinate clause.

Ничья is in the nominative case.

That is because it is the subject of получилась:

• получилась ничья = a draw resulted / it turned out to be a draw

A learner might expect another case because English often uses structures like it ended in a draw, but in Russian the noun here is treated as the subject of the verb.

Yes, that is possible.

• спорили, почему получилась ничья = they argued why it was a draw
• спорили о том, почему получилась ничья = they argued about why it was a draw

The version without о том is more direct and very natural. Adding о том makes the connection more explicit, but it is not necessary here.

No, Russian word order is fairly flexible.

The given sentence is neutral and natural:

• Болельщики на трибуне спорили, почему получилась ничья.

But Russian could also rearrange parts for emphasis, for example:

• На трибуне болельщики спорили, почему получилась ничья.

This would put a little more focus on where the action happened.

So the original order is not the only possible one, but it is a normal default choice.