Плейлист обновили после заказа песни.

Because плейлист is not the subject here — it is the direct object.

The verb обновили is a past tense plural form, and in this kind of sentence Russian often uses 3rd person plural with no subject stated to mean something like:

• they updated the playlist
• someone updated the playlist
• the playlist was updated

This is a very common Russian pattern when the person who did the action is unknown, unimportant, or just not mentioned.

It is the object.

A learner might expect the first noun in the sentence to be the subject, but here the grammar shows otherwise:

• обновили = they updated
• so there is an implied doer, not written out
• плейлист is what got updated

So the structure is basically:

• [Someone] updated [the playlist] after the song request/order.

Also, плейлист is masculine and inanimate, so in the accusative singular it looks exactly like the nominative singular. That is why the form itself does not visibly change.

Because Russian often leaves out subjects when they are understood from the verb form.

In this sentence, обновили already tells you that the action was done by an unspecified they. Russian does this much more freely than English.

So instead of saying:

• Они обновили плейлист...

Russian can simply say:

• Плейлист обновили...

This often sounds more natural when the doer is not important.

Обновили is the perfective past tense of обновить.

Perfective aspect is used because the sentence presents the update as a completed action:

• the playlist got updated
• the action happened and is viewed as finished

If you used the imperfective обновляли, it would suggest something more like:

• they were updating it
• they used to update it
• they updated it repeatedly
• the action is being described as a process rather than a completed event

Here, the perfective fits best because the sentence describes a single completed result.

Because the preposition после requires the genitive case.

So:

• заказ → nominative
• после заказа → genitive after после

This is just a rule of government:

• после + genitive

Other examples:

• после урока = after the lesson
• после фильма = after the film
• после работы = after work

So после заказа means after the order/request.

Because песни depends on заказа.

The phrase заказ песни means literally the ordering/requesting of a song or a song request/order.

So the pattern is:

• заказ = order/request
• заказ песни = order/request of a song

When заказ becomes genitive after после, the whole phrase becomes:

• после заказа песни

The noun песни stays genitive because it is linked to заказа as of a song.

It usually means requesting a song or ordering a song to be played.

The exact English wording depends on context. It could mean something like:

• a listener requested a song
• someone ordered a song in a karaoke bar / restaurant / radio program / DJ setting
• a song request was made

So заказ here is not necessarily a commercial purchase. It often refers to asking for a song to be played.

Yes. Even though the Russian sentence is not a grammatical passive, English often translates it naturally that way.

Possible translations:

• They updated the playlist after the song request.
• The playlist was updated after the song request.

Russian often uses this indefinite-personal construction where English may prefer a passive.

So grammatically in Russian it is more like they updated, but in meaning it can work very much like was updated.

Yes, it could be changed.

Russian word order is fairly flexible, and different orders shift the focus slightly.

This version puts плейлист first, which makes it the topic or focus of attention:

• Плейлист обновили после заказа песни.

You could also say:

• После заказа песни обновили плейлист.

That version starts with the time circumstance after the song request.

Both are grammatical. The original feels natural if the conversation is already about the playlist.

Russian has no articles like a or the.

So плейлист can mean:

• a playlist
• the playlist

and песни can correspond to:

• a song
• the song

The exact meaning comes from context.

In this sentence, English will often use the playlist because it sounds like a specific playlist already known in the situation. Likewise, a song request or the song request may both be possible depending on context.

Yes. A more explicitly passive version would be:

• Плейлист был обновлён после заказа песни.

That means more directly:

• The playlist was updated after the song request.

The difference is mostly stylistic:

• Плейлист обновили... = more common, conversational, focuses less on who did it
• Плейлист был обновлён... = more formal, more explicitly passive

Russian often prefers the first version in everyday usage.

Yes, absolutely.

You could say:

• Плейлист обновили после того, как заказали песню.

This means:

• The playlist was updated after they ordered/requested a song.

Compared with после заказа песни, this version is:

• more explicit
• more verbal
• a bit longer
• sometimes more natural in speech if you want to emphasize the action itself

The original sentence uses a compact noun phrase, which is very common in Russian.

A useful way to break it down is:

• Плейлист = direct object
• обновили = past plural verb with unspecified subject
• после заказа песни = time phrase, after the song request/order

So the sentence pattern is roughly:

• [Object] + [they did something] + [after X]

More literally:

• Playlist updated-they after request/order of song

More naturally in English:

• They updated the playlist after the song request.
• The playlist was updated after a song was requested.