Večeras ću slušati muziku i čitati poruke na računaru.

Because ću is a clitic, and Serbian clitics usually go in the second position of the sentence or clause.

So in:

Večeras ću slušati muziku i čitati poruke na računaru.

the first element is Večeras and the clitic ću comes right after it.

You could also say:

Ja ću večeras slušati muziku...

Here, Ja is the first element, so ću comes after Ja.

This is a very common Serbian word-order pattern.

Because Serbian forms the future tense here with:

ću + infinitive

So:

• ću slušati = I will listen
• ću čitati = I will read

In this sentence, one ću works for both verbs:

Večeras ću slušati muziku i čitati poruke...
= Tonight I will listen to music and read messages...

This is completely normal.

It is in the future tense, specifically futur I.

The pattern is:

• ću = auxiliary meaning will
• slušati / čitati = infinitives

So the whole sentence means something like:

Tonight I will listen to music and read messages on the computer.

Because Serbian often drops subject pronouns when they are clear from the verb form.

Here, ću already tells you the subject is I.

So:

• Večeras ću slušati... = Tonight I will listen...
• Ja ću večeras slušati... = also possible, but ja is added only if you want emphasis or contrast.

English usually needs I, but Serbian often does not.

They are in the accusative case because they are direct objects of the verbs.

• slušati muziku = to listen to music
• čitati poruke = to read messages

Dictionary forms are:

• muzika → muziku in the accusative singular
• poruka → poruke in the accusative plural

A learner should get used to this: after many verbs, the noun changes form because of case.

Because muzika is a feminine noun, and as a direct object in the singular, it takes the accusative form muziku.

So:

• nominative: muzika = music
• accusative: muziku = music, as the thing being listened to

Compare:

• Muzika je glasna. = The music is loud.
• Slušam muziku. = I am listening to music.

Poruke is plural here.

The singular is:

• poruka = message

The plural is:

• poruke = messages

In this sentence it is also the accusative plural, and for this noun that form looks the same as the nominative plural.

So:

• poruka = message
• poruke = messages

Na računaru literally means on the computer, and that is the normal Serbian way to say that something is being done using a computer or happening on a computer screen/device.

The noun is:

• računar = computer

After na in this meaning, Serbian uses the locative case:

• na računaru

So:

• čitati poruke na računaru = to read messages on the computer

Using u računaru would usually sound like inside the computer, which is not what is meant here.

It is in the locative case.

The preposition na can take different cases depending on meaning, but here it means something like on / at, describing location or where the activity happens, so Serbian uses the locative:

• računar → računaru

That is why the sentence says:

na računaru

No, večeras is best learned as an adverb meaning this evening / tonight.

It does come historically from veče or večer, but in modern usage learners should treat večeras as a fixed time word.

Similar time adverbs include:

• danas = today
• jutros = this morning
• večeras = tonight / this evening

Yes. Serbian word order is fairly flexible, and you can change the order to highlight different things, as long as the structure is still clear.

For example:

• Večeras ću slušati muziku i čitati poruke na računaru.
• Večeras ću čitati poruke i slušati muziku na računaru.

Both are grammatical. The main difference is just what comes first in focus.

However, be careful with where na računaru attaches. In the original sentence, it most naturally goes with čitati poruke. If you move things around, the meaning can become slightly less clear.

Most naturally, it applies mainly to čitati poruke.

So the sentence is usually understood as:

Tonight I will listen to music and read messages on the computer.

That sounds like:

• listen to music
• read messages on the computer

If you wanted to make it very clear that both actions are happening on the computer, you might rephrase the sentence.

This is a very common learner question.

• slušati = to listen
• čuti = to hear

So:

• slušati muziku = to listen to music
• čuti muziku = to hear music

In this sentence, slušati is correct because it describes an intentional activity.

A few sounds here are important:

• č sounds roughly like ch in chocolate, but a bit harder
• ć is softer than č
• š sounds like sh
• ž sounds like the s in measure

So roughly:

• ću = a soft chu sound
• čitati = chee-ta-ti
• računaru = roughly ra-chu-na-ru

Also:

• muziku = moo-zee-koo
• poruke = po-roo-ke

These are only rough English approximations, but they help at the beginning.

Because Serbian does not use articles like English does.

So:

• muziku can mean music, the music, or sometimes some music, depending on context
• poruke can mean messages or the messages

Context tells you how specific the meaning is.

This is something English speakers need to get used to, because Serbian leaves that information unstated unless needed.

Računar is the standard Serbian word for computer.

You may also hear:

• kompjuter

but računar is very common and fully standard. In this sentence, na računaru is perfectly natural Serbian.