Kad radim popodnevnu smjenu, često ostajem prekovremeno, pa ne stignem na kavu.

Here kad means when, but in a sentence like this it often has the sense of whenever because the whole statement is habitual.

So:

• Kad radim popodnevnu smjenu = When/Whenever I work the afternoon shift

Croatian often uses kad in everyday speech, while kada is the longer form. Both are correct, but kad is very common and natural in conversation.

In Croatian, the present tense is very commonly used for habits and repeated actions, just like in English:

• Kad radim... = When I work...
• često ostajem... = I often stay...
• ne stignem... = I don’t manage...

So the present here does not mean only right now. It can also describe something that regularly happens.

Because smjenu is in the accusative singular.

The noun is:

• nominative: popodnevna smjena = an afternoon shift
• accusative: popodnevnu smjenu

Here it is accusative because it is the object of radim in the sense of working a shift:

• raditi smjenu = to work a shift

Since smjena is a feminine noun, both the adjective and noun change:

• popodnevna smjena → popodnevnu smjenu

Yes. In Croatian, it is normal to say:

• raditi jutarnju smjenu = to work the morning shift
• raditi noćnu smjenu = to work the night shift
• raditi popodnevnu smjenu = to work the afternoon shift

So smjena means shift, and raditi smjenu is a very natural expression.

It means I stay/work overtime.

• ostajem = I stay / I remain
• prekovremeno = overtime

Together, ostajati prekovremeno is a common way to say that someone stays longer at work than their regular hours.

A very literal translation would be something like I stay overtime, but in natural English we usually say I stay late or I work overtime.

Here prekovremeno functions adverbially, describing how or in what way the person stays.

Compare:

• prekovremeni rad = overtime work
  Here prekovremeni is an adjective modifying rad.

• ostati prekovremeno = to stay/work overtime
  Here prekovremeno works like an adverb.

So in this sentence, the adverb form is the natural choice.

Here pa means something like:

• so
• and so
• which means that
• and then as a result

In this sentence it links cause and consequence:

• često ostajem prekovremeno, pa ne stignem na kavu
• I often stay overtime, so I don’t make it for coffee

It is not exactly the same as simple and. Pa suggests that the second part follows naturally from the first.

Ne stignem means I don’t manage, I don’t make it, or I don’t have enough time to get there/do it.

That is different from ne mogu, which means I can’t in a broader sense.

Compare:

• Ne mogu doći. = I can’t come.
  This could mean I’m unable, not allowed, too tired, busy, etc.

• Ne stignem doći. = I don’t manage to come / I don’t make it in time.
  This specifically suggests a lack of time or schedule pressure.

So ne stignem na kavu is very natural here because the problem is that overtime causes a time conflict.

Na kavu is na + accusative.

The noun is:

• nominative: kava = coffee
• accusative: kavu

This expression is idiomatic and very common:

• ići na kavu = to go for coffee
• doći na kavu = to come for coffee
• stići na kavu = to make it for coffee

With na, Croatian often uses the accusative when there is movement toward an event, destination, or activity. Here na kavu is best understood as for coffee / to a coffee meet-up, not just the drink itself.

Very often it means the social event, not just the beverage.

In Croatian, ići na kavu can mean:

• going out for coffee
• meeting someone for a coffee
• having a casual chat in a café

So ne stignem na kavu often implies I don’t make it to the coffee meet-up or I don’t have time to go out for coffee.

Yes. Croatian word order is flexible, although the original order sounds very natural.

Original:

• Kad radim popodnevnu smjenu, često ostajem prekovremeno, pa ne stignem na kavu.

Possible variation:

• Često ostajem prekovremeno kad radim popodnevnu smjenu, pa ne stignem na kavu.

This still means the same thing, but the emphasis shifts slightly. The original version foregrounds the condition when I work the afternoon shift.

So the word order can change, but not completely freely: you still want the sentence to sound natural and keep the logical flow.

Almost always in everyday use, yes.

• kad = shorter, very common, conversational, natural
• kada = longer, a bit more formal or careful

In this sentence, both would work:

• Kad radim popodnevnu smjenu...
• Kada radim popodnevnu smjenu...

Most speakers would probably prefer kad in ordinary speech.

It describes a general pattern or habitual situation.

Several things show that:

• kad = when/whenever
• često = often
• all the verbs are in the present tense

So the meaning is not Today I am working an afternoon shift and staying late. Instead, it means something like:

• Whenever I work the afternoon shift, I often have to stay overtime, so I don’t make it for coffee.