Atak zaczyna się teraz.

Atak is in the nominative singular form because it is the subject of the sentence.

• atak = attack
• In Atak zaczyna się teraz, the thing that is beginning is the attack, so Polish uses the basic dictionary form here.

Because atak is a masculine inanimate noun, its nominative singular form is atak.

Because zaczyna się means begins / is beginning in the sense that something starts by itself or comes into its beginning.

Compare:

• zaczynać coś = to start something
• zaczynać się = to begin / to start

So:

• Dowódca zaczyna atak = The commander starts the attack
• Atak zaczyna się = The attack begins

In your sentence, atak is not starting something else. It is the thing that is beginning, so się is needed.

Się is a very common Polish particle used with many verbs. In this sentence, it helps form the verb zaczynać się, which means to begin.

It does not always translate directly as oneself or itself in natural English. Here, it is simply part of the verb’s normal meaning.

So it is best to learn:

• zaczynać = to start
• zaczynać się = to begin

rather than trying to translate się word-for-word every time.

It is present tense.

The verb here is from zaczynać się and the form zaczyna się means:

• begins
• is beginning
• sometimes starts, depending on context

Because Polish present tense often covers both simple present and present progressive meanings, zaczyna się can correspond to either:

• The attack begins now
• The attack is beginning now

The verb zaczynać się is imperfective. In Polish, imperfective verbs are normally used for the present tense.

That is why:

• zaczyna się = present, is beginning / begins
• zacznie się = future, from the perfective verb zacząć się

Polish perfective verbs do not have a true present tense. Their present-looking forms usually have future meaning.

So:

• Atak zaczyna się teraz = The attack is beginning now
• Atak zacznie się teraz = The attack will begin now

Even though English might treat begin as a single event, Polish still uses the imperfective in the present when the event is unfolding now.

Yes, that is also possible.

Both of these are natural:

• Atak zaczyna się teraz
• Atak się zaczyna teraz

The difference is mostly about word order and emphasis, not basic meaning.

In neutral statements, się often comes after the verb, but Polish word order is fairly flexible. You should know, though, that się usually does not go at the very beginning of a sentence.

So this would sound wrong or very unnatural:

• Się atak zaczyna teraz

Polish word order is more flexible than English word order. Teraz is at the end here because that is a very natural place for adverbs of time.

The sentence can be rearranged, with slightly different emphasis:

• Atak zaczyna się teraz = neutral, natural
• Teraz zaczyna się atak = emphasis on now
• Teraz atak się zaczyna = also possible, a bit more marked

English relies more strongly on fixed word order. Polish can move elements around to highlight what is new, important, or contrastive.

Because Polish does not have articles like a and the.

So atak can mean:

• an attack
• the attack

The context tells you which one is meant.

In Atak zaczyna się teraz, English will often naturally translate it as The attack is beginning now, but Polish does not need a separate word for the.

A rough pronunciation guide is:

• zaczyna ≈ za-CHI-na
• się ≈ something like shyem, but shorter and more nasal

A few useful points:

• cz sounds roughly like ch in chop
• y is not the same as English ee; it is a more central vowel
• się is pronounced with a soft ś sound, similar to a soft sh
• ę at the end is often not pronounced as a full nasal vowel in normal speech; it may sound closer to e with some nasal coloring

Stress in Polish usually falls on the second-to-last syllable:

• a-TAK
• za-czy-NA
• TE-raz

They are very similar.

• Atak zaczyna się teraz = The attack is beginning now
• Atak rozpoczyna się teraz = also The attack is beginning now

But rozpoczyna się can sound a bit more formal, official, or elevated in some contexts.
Zaczyna się is very common and neutral.

So if you are learning everyday Polish, zaczyna się is an excellent form to know.

Yes.

Polish present-tense forms often cover both meanings that English separates into:

• simple present: begins
• present continuous: is beginning

So Atak zaczyna się teraz can match either one, depending on context and style.

In many situations, English would prefer is beginning now, because begins now can sound more formal or dramatic.

No. Zaczął się is past tense.

• Atak zaczyna się teraz = The attack is beginning now
• Atak zaczął się teraz = literally The attack started now, which usually does not sound natural unless teraz means something like just now

A more natural English rendering of Atak zaczął się teraz would often be:

• The attack has just started
• The attack started just now

So changing zaczyna się to zaczął się changes the time reference.

Yes. Atak zaczyna się teraz is a complete, natural Polish sentence.

It has everything needed:

• Atak = subject
• zaczyna się = verb
• teraz = time expression

It sounds like something you might hear in narration, military context, a game, a film, or any dramatic situation where an attack is starting.