После сигнала судьи нападающий будет бить пенальти.

Because после requires the genitive case.

• Dictionary form: сигнал
• Genitive singular: сигнала

So после сигнала means after the signal.

This is a very common pattern in Russian:

• после урока — after the lesson
• после матча — after the match
• после игры — after the game

Here судьи means of the referee or the referee’s.

So the phrase сигнала судьи is literally:

• сигнала — of the signal
• судьи — of the referee

Together: the referee’s signal.

Russian often expresses possession this way instead of using an apostrophe like English does.

• книга студента — the student’s book
• голос тренера — the coach’s voice
• сигнал судьи — the referee’s signal

It is in the nominative singular masculine.

In this sentence, нападающий is the subject, so nominative is used.

Although the word originally looks like an adjective/participle meaning attacking, it is very commonly used as a noun in sports to mean:

• forward
• attacker
• striker (depending on the sport/context)

So here it functions like a normal noun: the forward / attacker.

In this sentence, it is being used as a noun.

Russian often turns adjectives or participle-like forms into nouns when the meaning is obvious from context. This is called substantivization.

So:

• нападающий игрок would mean attacking player
• but simply нападающий means the attacker / forward

English does something similar sometimes, though less often, as in the poor, the accused, or the injured.

Because бить is an imperfective verb, and the future of imperfective verbs is formed with быть + infinitive:

• будет бить — will be kicking / will kick

This is called the compound future.

Russian has two future patterns:

1. Imperfective future
   будет бить
2. Perfective future
   a single verb form, for example ударит

The choice depends on aspect.

Here будет бить пенальти sounds natural if the speaker is presenting the action as an upcoming event/process in context. In sports language, this can work well.

The difference is mainly aspect and how the action is viewed.

• будет бить пенальти uses the imperfective
• ударит пенальти uses the perfective

Very roughly:

• будет бить пенальти = the attacker will be taking the penalty / is about to take the penalty
• ударит пенальти = the attacker will strike the penalty kick

The imperfective version can sound a bit more focused on the event as part of the situation or sequence. The perfective version can sound more like a single completed action.

In real sports commentary, both kinds of phrasing may appear depending on style and context.

Because пенальти is an indeclinable noun in Russian.

That means it keeps the same form in different cases.

Here it is the direct object, so logically it is in the accusative, but the form still stays пенальти.

This is common with many borrowed words in Russian.

For example, compare:

• Я вижу такси. — I see a taxi.
• Мы обсуждаем жюри. — We are discussing the jury.
• Он будет бить пенальти. — He will take a penalty.

The case is determined by function, even if the word itself does not change form.

In sports Russian, бить пенальти is an idiomatic way to say to take a penalty or to kick a penalty.

The verb бить literally means to hit, to strike, or to beat, but in sports it is often used for striking the ball:

• бить по воротам — to shoot at the goal
• бить штрафной — to take a free kick
• бить пенальти — to take a penalty

So this is normal sports language, not a strange literal translation.

Because Russian has no articles.

English uses:

• the referee
• a referee
• the attacker
• a signal

Russian usually leaves this information to context.

So судьи can mean:

• of the referee
• of a referee

and нападающий can mean:

• the attacker
• an attacker

In this sentence, the context probably makes it definite, so English naturally uses the.

No, Russian word order is fairly flexible, though this sentence has a very normal neutral order:

После сигнала судьи нападающий будет бить пенальти.

This order presents the information smoothly:

1. time/context — После сигнала судьи
2. subject — нападающий
3. verb — будет бить
4. object — пенальти

You could change the order for emphasis, for example:

• Нападающий будет бить пенальти после сигнала судьи.
• Пенальти нападающий будет бить после сигнала судьи.

But the original sentence sounds very natural and neutral.

A helpful stress pattern is:

ПослЕ сигнАла судьИ нападАющий бУдет бить пенАльти.

Word stresses:

• после
• сигнала
• судьи
• нападающий
• будет
• бить
• пенальти

A rough pronunciation guide:

• pos-LYE
• sig-NA-la
• soo-DYI
• na-pa-DA-yu-shchiy
• BOO-det
• beet
• pe-NAL-ti

The exact sounds are best learned by listening, but the stress is especially important in Russian.

Not necessarily immediately, but it strongly means after the referee’s signal as the relevant next event.

Whether it is immediate or just subsequent depends on context.

In a football context, it will usually be understood as something like:

• once the referee gives the signal,
• then the attacker will take the penalty.

So in practice, it often does imply a close sequence, even though после by itself simply means after.

It is possible in some situations to say сигнал от кого-то, but here сигнал судьи is the natural and standard way.

Why?

Because Russian usually expresses this kind of possession/source with a noun in the genitive:

• совет тренера — the coach’s advice
• приказ командира — the commander’s order
• сигнал судьи — the referee’s signal

Using от here would sound less natural for this specific phrase.