Ja sada ne pijem kafu.

That’s true: Serbian often leaves out subject pronouns because the verb already shows who is doing the action.

• pijem already means I drink / I am drinking
• So Ja sada ne pijem kafu and Sada ne pijem kafu can both be correct

Including ja can:

• add emphasis: I’m not drinking coffee now
• create contrast: I’m not drinking coffee now, but someone else is
• make the sentence sound slightly more explicit

So ja is optional here, not required.

sada means now.

In this sentence, it shows that the action is true at this moment or currently:

• Ja sada ne pijem kafu = I’m not drinking coffee now

Its position is fairly flexible. You could also hear:

• Sada ne pijem kafu
• Ja ne pijem kafu sada

The version with sada before ne pijem is very natural.

In Serbian, negation is usually made with the separate word ne placed before the verb.

So:

• pijem = I drink / I am drinking
• ne pijem = I do not drink / I am not drinking

This is normal Serbian grammar:

• radim → ne radim
• znam → ne znam
• idem → ne idem

So ne pijem is exactly what you should expect.

pijem is the 1st person singular present tense of piti (to drink).

So:

• ja pijem = I drink / I am drinking

A few present-tense forms of piti are:

• ja pijem = I drink
• ti piješ = you drink
• on/ona/ono pije = he/she/it drinks
• mi pijemo = we drink
• vi pijete = you drink
• oni/one/ona piju = they drink

Because kafu is the accusative singular form, and here coffee is the direct object of the verb to drink.

• dictionary form: kafa = coffee
• accusative singular: kafu

Since you are drinking the coffee, Serbian uses the object case:

• Pijem kafu = I’m drinking coffee
• Volim kafu = I like coffee

This is a very common pattern in Serbian: feminine nouns ending in -a often change to -u in the accusative singular.

It can mean either, depending on context.

Serbian has no articles, so there is no direct equivalent of a or the.

So kafu could mean:

• coffee in general
• a coffee
• the coffee

In everyday speech, piti kafu often means:

• to drink coffee in general
• to have a cup of coffee

The exact meaning depends on the situation.

It can mean either one, depending on context.

Because Serbian present tense with an imperfective verb can cover both:

• an action happening now
• a general or current habit

So Ja sada ne pijem kafu can mean:

• I’m not drinking coffee right now
• I’m not drinking coffee these days / at the moment

The word sada strongly suggests a current time frame, but context decides whether that means this exact moment or a broader currently.

piti is the imperfective verb, and that is the normal choice for a present-time action or habit.

• piti = to drink, to be drinking
• popiti = to drink up / to drink completely / to have a drink (perfective)

In Serbian, perfective verbs usually do not describe an action happening right now in the present.

So:

• Ne pijem kafu = natural for I’m not drinking coffee
• Ne popijem kafu would not normally mean that

If you want a present negative statement about drinking coffee, ne pijem is the correct form.

No, Serbian word order is more flexible than English word order.

This sentence can appear in different orders, for example:

• Ja sada ne pijem kafu
• Sada ne pijem kafu
• Ja ne pijem kafu sada
• Kafu sada ne pijem (more marked, more emphasis on coffee)

However, not all versions sound equally neutral.
Ja sada ne pijem kafu is a natural, standard order.

Word order in Serbian often changes the focus or emphasis, not the basic meaning.

Yes, absolutely.

Ne pijem kafu is a complete and natural sentence:

• I’m not drinking coffee
• I don’t drink coffee

Adding ja and sada gives extra information:

• ja = emphasis on I
• sada = emphasis on now / currently

So the longer sentence is not wrong at all; it is just more specific.

A helpful approximation for English speakers is PEE-yem.

More exactly:

• pi sounds like pee
• je sounds roughly like ye in yes, but blended into the word
• the whole word is pi-jem

So:

• pijem ≈ PEE-yem

Also:

• j in Serbian is pronounced like English y
• so pi-jem, not pee-jem with a hard English j

It is neutral and works in both formal and informal situations.

Nothing in Ja sada ne pijem kafu is especially casual or especially formal. It is just standard Serbian.

What changes formality more often in Serbian is:

• how you address someone (ti vs. Vi)
• vocabulary choice
• overall sentence style

This sentence itself is perfectly normal in everyday speech and also acceptable in careful standard language.