Learn Hardcore Croatian: Na karti vidimo sjever, jug, istok i zapad našeg grada. - On the map we see the north, south, east and west of our city.

With static location, na is used with the locative case, which is why we get karti:
- na
  - locative → na karti = on the map
With movement onto something, na would take the accusative:
- staviti nešto na kartu = to put something onto the map

You would use u (in) for being inside something:

u gradu = in the city
u knjizi = in the book

A map is thought of as a flat surface you look on, not something you are in, so Croatian uses na karti.

Why is it karti and not karta? What case is that?

The base form is karta (map), a regular feminine noun ending in -a.

Here it appears as karti because it is in the locative singular, required by na when it expresses location (“on”).

Declension of karta (singular):

Nominative: karta (the map – subject)
Genitive: karte (of the map)
Dative: karti (to/for the map)
Accusative: kartu (see the map)
Vocative: karto
Locative: karti (on/about the map)
Instrumental: kartom (with a map)

So na karti literally = on (the) map in the locative case.

What does vidimo mean exactly, and why is there no word for we?

Vidimo is the 1st person plural present tense of the verb vidjeti (to see).

Conjugation (present) of vidjeti:

ja vidim – I see
ti vidiš – you see
on/ona/ono vidi – he/she/it sees
mi vidimo – we see
vi vidite – you (pl./formal) see
oni/one/ona vide – they see

Croatian usually omits subject pronouns (like mi = we) because the verb ending already shows who the subject is.

So:

Mi vidimo = We see
Vidimo = (We) see

In this sentence, vidimo clearly means we see from the verb ending -imo, so mi is not needed.

Could I change the word order and say Vidimo na karti sjever, jug, istok i zapad našeg grada? Is that still correct?

Yes, that is grammatically correct. Croatian word order is relatively flexible.

The original:

Na karti vidimo sjever, jug, istok i zapad našeg grada.
- Slight emphasis on the location: On the map, we see…

Your version:

Vidimo na karti sjever, jug, istok i zapad našeg grada.
- Slightly more neutral; the first focus is on what we see.

Other possible, still natural orders:

Na karti sjever, jug, istok i zapad našeg grada vidimo. (more marked/emphatic)
Sjever, jug, istok i zapad našeg grada vidimo na karti. (emphasis on what we see)

So changing the word order is possible; it mostly affects emphasis and rhythm, not basic meaning.

Are sjever, jug, istok, zapad in the nominative or accusative here?

They are actually in the accusative singular, functioning as direct objects of vidimo (“we see”).

However, for inanimate masculine nouns, the accusative singular looks the same as the nominative. So you don’t see a visible change:

Nominative: sjever, jug, istok, zapad
Accusative: sjever, jug, istok, zapad (same form)

Compare with a feminine noun, where you would see the change:

Nominative: knjiga (book)
Accusative: knjigu

So grammatically they are objects in the accusative, but their forms match the nominative.

What does našeg grada mean exactly, and why is it in that form?

Našeg grada means “of our city”.

Grammatically:

grad = city, town (masculine noun)
grada = genitive singular of grad → of the city
naš = our (possessive adjective)
našeg = genitive singular masculine form of naš, agreeing with grada

So:

naš grad = our city (nominative)
našeg grada = of our city (genitive)

Why genitive? Because we’re specifying whose north, south, east and west:

sjever, jug, istok i zapad našeg grada
= the north, south, east and west of our city

The genitive is the usual case for possession or belonging in Croatian.

Why not just say sjever, jug, istok i zapad naš grad?

Naš grad is nominative and means simply our city (as a subject or direct object), not of our city.

Your version:

sjever, jug, istok i zapad naš grad
would sound ungrammatical or at least very odd, because naš grad is not connected correctly to the other nouns.

You want a phrase that behaves like “our city’s north, south, east and west” or “the north, south, east and west of our city”. For that, Croatian uses the genitive:

sjever, jug, istok i zapad našeg grada

So našeg grada is the right choice here.

Why is there no word for the (like “on the map”, “of our city”)? Does Croatian not use articles?

Croatian has no articles like English a/an and the.

karta can mean a map or the map, depending on context.
na karti can be understood as on a map or on the map.
naš grad can mean our city in both definite and indefinite senses; definiteness is usually clear from context, not grammar.

In this sentence, English needs the:

On the map we see the north, south, east and west of our city.

Croatian expresses the same idea without any article:

Na karti vidimo sjever, jug, istok i zapad našeg grada.

What is the role of našeg exactly? How does it agree with grada?

Našeg is the genitive singular masculine form of the possessive adjective naš (our).

Agreement rules:

Gender: grad is masculine → naš must be in a masculine form.
Number: grad is singular → naš must be singular.
Case: grad is in the genitive (grada) → naš must also be in the genitive (našeg).

So the combination is:

Masc. sing. genitive: našeg grada

This is a core pattern in Croatian: adjectives and possessive adjectives must match the nouns they modify in gender, number, and case.

Could we just say Na karti vidimo sjever, jug, istok i zapad. without našeg grada?

Yes, that would be grammatically correct:

Na karti vidimo sjever, jug, istok i zapad.
→ On the map we see north, south, east and west.

However, the meaning becomes more general: just the four cardinal directions, not specifically of our city.

With našeg grada, the sentence is more specific:

We are talking about the parts of our city corresponding to the north, south, east and west.

Is there any difference between karta and mapa or plan in this context?

All three can be used, but there are nuances:

karta – the most common general word for map
- zemljopisna karta = geographical map
mapa – also “map”, often used, sometimes a bit more technical or international-sounding
plan – often a detailed city map or layout
- plan grada = city plan/street map

You might hear:

Na karti vidimo… (very natural)
Na mapi vidimo… (also used; style/region dependent)
Na planu grada vidimo… (specifically “on the city plan/map…”)

In your sentence, karta is perfectly standard.

Why are there commas between sjever, jug, istok but no comma before “i zapad”?

Croatian uses commas in lists much like English, but usually does not use an “Oxford comma”.

Pattern in a simple list:

item 1, item 2, item 3 i item 4

So:

sjever, jug, istok i zapad

No comma before i (“and”) is the standard rule in Croatian for a simple list like this.