Learn Hardcore Croatian: Na mreži sam potpisala još jednu peticiju, ovaj put za bolji javni prijevoz u našem gradu. - On the internet I signed another petition, this time for better public transport in our city.

The present tense of biti (to be):
- sam, si, je, smo, ste, su
The L‑participle of the main verb (here: potpisala from potpisati – “to sign”).

So sam potpisala literally corresponds to “I am signed” but functions like English “I signed”.

sam = I am (1st person singular, present)
potpisala = signed (past participle, feminine)

You cannot say just potpisala on its own in standard Croatian for a normal past tense; you need the auxiliary sam (unless it’s omitted in very casual speech, which is another story).

Why is it potpisala and not potpisao?

The ending of potpisala shows the gender of the speaker:

potpisao – masculine singular
potpisala – feminine singular
potpisali – masculine/mixed plural
potpisale – feminine plural

Since the sentence uses potpisala, it implies the speaker is female.
A man would say: Na mreži sam potpisao još jednu peticiju…

Croatian often drops the pronoun ja (“I”), and you know who is speaking (male or female) from this participle ending.

What does Na mreži literally mean, and is it the same as “online”?

Literally, na mreži means “on the network” or “on the net”. In everyday language it’s used like “online”.

Common alternatives you’ll hear:

na internetu – on the internet (very common)
online – the English word, used a lot in informal speech
preko interneta – via the internet

All of these could replace Na mreži here without really changing the meaning:

Na internetu sam potpisala…
Online sam potpisala…

What exactly does još jednu mean in još jednu peticiju?

Here još jednu means “another one” or “one more”.

još can mean still, yet, or more depending on context.
jednu is the accusative feminine form of jedan (“one”) and agrees with peticiju (petition), which is also feminine accusative singular.

So:

još jednu peticiju = one more petition / another petition.

If it were the subject (not object), you’d see:

još jedna peticija = one more petition (is…)
But as a direct object, it becomes još jednu peticiju.

Why is it peticiju and not peticija?

The dictionary form peticija is nominative singular (used for subjects).

In this sentence, peticiju is the direct object of potpisala (what did she sign?), so it must be in the accusative case:

Nominative: peticija – the petition (is)
Accusative: peticiju – I signed the petition

Feminine nouns ending in -cija (demokracija, aplikacija, peticija…) typically change -a → -u in the accusative singular.

Why is there a comma before ovaj put? Is it necessary?

The comma separates ovaj put za bolji javni prijevoz u našem gradu as an added piece of information – a kind of side remark: “…another petition, this time for better public transport…”.

With the comma: it sounds like an extra comment, with a small pause.
Without the comma: Na mreži sam potpisala još jednu peticiju ovaj put za bolji javni prijevoz… – still correct; it just flows a bit more as one continuous piece of information.

So the comma is optional here and mostly reflects the writer’s sense of rhythm and emphasis, not a hard grammatical rule.

What’s the difference between ovaj put and ovog puta?

Both ovaj put and ovog puta mean “this time”, and both are very common.

ovaj put – this time (literally “this occasion”, nominative)
ovog puta – this time (genitive form; literally “of this time/occasion”)

In many contexts they’re interchangeable:

Ovaj put sam potpisala peticiju.
Ovog puta sam potpisala peticiju.

In your sentence, ovaj put za bolji javni prijevoz… could also be ovog puta za bolji javni prijevoz… with no real change in meaning.

Why is it za bolji javni prijevoz and not za bolje javni prijevoz?

Bolji is the masculine comparative form of dobar (“good”):

dobar → bolji (masc)
dobra → bolja (fem)
dobro → bolje (neuter)

The noun prijevoz (“transport”) is masculine, so the adjective must be masculine too:

bolji prijevoz – better transport
(“bolje prijevoz” would be wrong, because bolje is the neuter form.)

Then we add javni (“public”), which also agrees with prijevoz (masculine accusative):

bolji javni prijevoz – better public transport

All of this is in accusative because of the preposition za (“for”), which takes the accusative case.

Why is the adjective order bolji javni prijevoz and not javni bolji prijevoz like in English “better public transport”?

In Croatian, adjective order is more flexible than in English, but here there is a reason:

javni prijevoz is a fixed collocation meaning “public transport”.
bolji then modifies that whole phrase: bolji (javni prijevoz) = better public transport.

So you can think of it as:

bolji [javni prijevoz]

Putting javni before bolji (javni bolji prijevoz) would sound odd and unnatural, because it breaks up the usual phrase javni prijevoz.

Why is it za bolji javni prijevoz, and not something like za boljeg javnog prijevoza?

Because of the preposition za, the noun phrase must be in the accusative, not genitive:

za + accusative: za koga? za što? – for whom? for what?
- za bolji javni prijevoz – for better public transport

Forms like boljeg javnog prijevoza are genitive, which you would use after different prepositions or in other roles (e.g. “without better public transport”: bez boljeg javnog prijevoza).

So:
za → accusative → bolji javni prijevoz.

Why is it u našem gradu and not u naš grad or u našemu gradu?

The preposition u can take accusative (movement into) or locative (location in):

u naš grad – into our city (movement, accusative)
u našem gradu – in our city (location, locative)

Here we mean “in our city”, so we use the locative case:

grad → gradu (locative singular)
naš → našem (the dative/locative/instrumental form of the possessive adjective)

Našemu is an older/very formal variant of našem; it’s grammatical but in everyday modern speech people almost always say našem gradu.

Could I say Potpisala sam još jednu peticiju na mreži instead? How flexible is the word order?

Yes, that’s perfectly correct:

Potpisala sam još jednu peticiju na mreži, ovaj put za bolji javni prijevoz u našem gradu.

Croatian word order is fairly flexible, and the placement of elements is often about emphasis and flow, not pure grammar.

Na mreži sam potpisala… – slightly emphasizes “on the internet”.
Potpisala sam na mreži… – more neutral, focusing first on the action “I signed”.

The clitic sam generally wants to be in second position in the sentence or clause (after the first stressed word or phrase), so both of these orders keep sam in a natural position.