Мой друг — талантливый музыкант, играющий на гитаре.

In the present tense, Russian usually leaves out the verb быть (to be) in simple sentences like this.

So:

Мой друг — талантливый музыкант
literally looks like
My friend — talented musician

but it means
My friend is a talented musician.

This is completely normal Russian.

The dash helps show the relationship between the subject and the predicate when Russian has a zero copula—in other words, when is is understood but not spoken.

Here both parts are noun phrases:

• Мой друг = the subject
• талантливый музыкант = what the subject is

So the dash marks that structure clearly in writing.

Because Russian words that describe nouns must agree with the noun in gender, number, and case.

In this sentence:

• мой agrees with друг
• талантливый agrees with музыкант
• играющий also agrees with музыкант

Both друг and музыкант are masculine singular nominative, so the describing words are also masculine singular nominative.

Because this is a simple present-tense identification sentence with an omitted is.

Russian often uses the nominative in this pattern:

• Он студент.
• Она врач.
• Мой друг — талантливый музыкант.

The form музыкантом is instrumental, and you would more naturally expect it with forms like:

• Он был музыкантом. = He was a musician.
• Он является музыкантом. = He is a musician / He is considered a musician.

So in your sentence, музыкант is the normal choice.

Играющий is a present active participle from the verb играть (to play).

It acts like an adjective and means something like:

• playing
• who plays

So:

музыкант, играющий на гитаре
means
a musician who plays the guitar

Not necessarily.

In this sentence, играющий на гитаре describes a characteristic of the musician, not necessarily an action happening at this exact moment.

So it is closer to:

a musician who plays guitar

than to:

a musician who is currently playing guitar right now

That is a very common point of confusion for English speakers.

Because играющий на гитаре is a participial phrase placed after the noun it modifies: музыкант.

In Russian, a participial phrase after the noun is usually set off by commas.

So:

талантливый музыкант, играющий на гитаре

is standard punctuation.

If the participial phrase came before the noun, the punctuation would often be different:

играющий на гитаре музыкант

Because with musical instruments, Russian normally uses:

играть на + prepositional case

So:

• играть на гитаре = to play the guitar
• играть на пианино = to play the piano
• играть на скрипке = to play the violin

Here гитара becomes гитаре, which is the prepositional singular form.

This is just the standard Russian pattern for instruments.

Yes.

You could say:

Мой друг — талантливый музыкант, который играет на гитаре.

That is grammatical and often feels more natural in everyday speech.

The version with играющий is more compact and can sound a bit more formal or written. Russian uses participles more comfortably than English does, but learners will often hear the который version more often in conversation.

Grammatically, it describes музыкант.

That is because it comes right after музыкант and agrees with it in form. So the structure is:

[Мой друг] — [талантливый музыкант, играющий на гитаре].

In meaning, of course, it still tells you something about your friend—but syntactically it modifies музыкант.

Because Russian has no articles.

There is no direct equivalent of English a or the in normal Russian grammar. Whether English uses a talented musician or the talented musician depends on context, not on a separate Russian word.

So талантливый музыкант can correspond to:

• a talented musician
• the talented musician

depending on the situation.