В субботу мы будем болеть за нашу команду на стадионе.

Because with days of the week, Russian usually uses в + accusative to mean on a certain day.

• суббота = Saturday
• в субботу = on Saturday

So this is a time expression, not a location expression.

Compare:

• в субботу = on Saturday
• в школу = to school
• в школе = in/at school

Here, субботу is the accusative form of суббота.

This is the compound future of an imperfective verb.

• болеть is imperfective
• Imperfective verbs form the future with быть in the future + infinitive

So:

• мы будем болеть = we will be cheering / we will be rooting

This is different from perfective future, which is usually one word. Here the speaker is talking about an action as a process or activity, not as a single completed event.

Yes, болеть has several meanings, and this is a very common point of confusion.

It can mean:

• to be ill
• to hurt / ache
• to root for / support a team, with за + accusative

So:

• Я болею = I am ill
• У меня горло болит = My throat hurts
• Я болею за нашу команду = I support / root for our team

In this sentence, болеть за is an idiomatic expression meaning to cheer for or to root for.

After болеть за in the sense of supporting a team or person, Russian uses за + accusative.

So:

• команда → команду (accusative singular)
• наша → нашу to match the noun

That is why we get:

• за нашу команду

This is just the normal pattern:

• болеть за кого? что?
  = to root for whom? for what?

Examples:

• болеть за Россию
• болеть за брата
• болеть за любимую команду

Russian often uses на with places that are thought of as venues, surfaces, or public event spaces.

So:

• на стадионе = at the stadium / in the stadium

This is simply the idiomatic choice in Russian. English might use at or in, but Russian normally says на стадионе.

Also, because this is a location meaning where?, the noun is in the prepositional case:

• стадион → на стадионе

Because the sentence presents cheering as an activity in progress or as something that will be happening, not as a completed result.

Imperfective is natural when talking about:

• ongoing actions
• repeated actions
• general activities
• actions viewed as a process

Cheering for a team at a stadium is typically seen as an activity over time, so будем болеть sounds natural.

A perfective verb here would change the meaning or sound unnatural in this context.

Yes. Russian often leaves out subject pronouns when they are clear from the verb form.

So both of these are possible:

• В субботу будем болеть за нашу команду на стадионе.
• В субботу мы будем болеть за нашу команду на стадионе.

Including мы can add a bit of clarity, contrast, or emphasis. Omitting it often sounds more natural in everyday speech if the subject is already obvious.

No, Russian word order is fairly flexible.

The neutral order here is:

• В субботу мы будем болеть за нашу команду на стадионе.

But other orders are possible depending on emphasis:

• Мы в субботу будем болеть за нашу команду на стадионе.
• На стадионе мы будем болеть за нашу команду в субботу.
• За нашу команду мы будем болеть на стадионе в субботу.

The basic meaning stays the same because the cases show the grammatical relationships. Word order mostly affects focus and style, not the core meaning.

It is the prepositional case after на when talking about location.

• стадион = nominative
• на стадионе = prepositional

This is the standard pattern for location:

• где? = where?
• на стадионе = at the stadium

Compare:

• на стадион = to the stadium (accusative, direction)
• на стадионе = at the stadium (prepositional, location)

Because the adjective has to agree with команду in:

• gender
• number
• case

The noun команда is:

• feminine
• singular
• accusative here

So the possessive adjective наш must become:

• нашу

Full agreement:

• за нашу команду

This is a standard adjective-noun agreement pattern in Russian.

The main stress pattern is:

• В суббОту
• мы бУдем
• болЕть
• за нАшу
• комАнду
• на стадиОне

A rough pronunciation guide:

• v soob-BOH-too
• mɨ BOO-dem
• ba-LYET'
• za NA-shoo
• ka-MAN-doo
• na stuh-dee-O-ne

A learner should especially watch:

• double бб in субботу
• stress in болеть
• stress in стадионе on -о-

In normal context, it naturally modifies the action будем болеть: the cheering will happen at the stadium.

Russian speakers will normally understand it as:

• Where will we be cheering?
  На стадионе.

It would not normally be interpreted as describing команду. If someone wanted to describe the team as being at the stadium, they would usually phrase the sentence differently.