Learn Hardcore Croatian: Prošli vikend razgovarala sam s njom u parku. - Last weekend I talked with her in the park.

The -la ending shows the speaker is feminine singular in the past tense. A male speaker would say razgovarao, not razgovarala. Plural would be razgovarali (mixed group or all-male) or razgovarale (all-female).

Where should sam go? Is the word order here natural?

Yes, it’s acceptable. The most neutral placement puts the clitic sam right after the first stressed element: Prošli vikend sam razgovarala s njom u parku. Your version, Prošli vikend razgovarala sam…, is also heard in speech and gives a bit of focus to the verb. Other natural orders include:

Razgovarala sam s njom u parku prošli vikend.
U parku sam prošli vikend razgovarala s njom.

Why is it s njom and not something like s nju?

Because s (with) requires the instrumental case. The feminine instrumental of ona (she) is njom (or njome). Nju is accusative and would be wrong after s.

Can I say sa njom instead of s njom?

Yes. S njom is the standard Croatian form; sa njom is also common, often used to make pronunciation smoother. Both are fine in everyday speech.

What’s the difference between njom and njome?

Both are instrumental of ona. Njom is the usual short form; njome is a bit longer and can sound slightly more formal or emphatic. Either works after s/sa.

Why is it u parku and not u park?

u
- locative (here: parku) = location (in the park).
u
- accusative (u park) = motion into (into the park). Since this sentence is about location, use locative: u parku.

Why does park become parku?

Masculine nouns like park take -u in the singular locative: nominative park, locative u parku.

Is Prošli vikend correct, or should it be Prošlog vikenda?

Both are correct and common:

Prošli vikend (accusative of time) is very common in speech.
Prošlog vikenda (genitive of time) is also frequent and can feel slightly more formal. Both mean “last weekend.”

Can I say zadnji vikend instead of prošli vikend?

People do say it, but zadnji can imply “final, the last one ever.” For “previous/last (most recent) weekend,” prošli vikend (or prethodni/protekli vikend) is clearer.

Does razgovarati mean the same as pričati or popričati?

razgovarati (s nekim) = to have a conversation (neutral, imperfective).
pričati = to talk/to tell (broader, often more casual).
popričati = to have a chat (single, completed action; perfective).
All are common; choice affects nuance and aspect.

How would the sentence change if the speaker is male?

Male speaker: Prošli vikend razgovarao sam s njom u parku.
Other persons for reference:

We: Razgovarali smo…
You (sg.): Razgovarao/razgovarala si…
They: Razgovarali su…

Do I need to say ja?

No. Croatian usually drops subject pronouns. Ja sam razgovarala… adds emphasis on “I” (e.g., not someone else).

How do I make it negative?

Use nisam (the negative of jesam):
Prošli vikend nisam razgovarala s njom u parku.
The clitic nisam still goes in the clitic slot near the start.

Can I move the time and place around?

Yes, Croatian word order is flexible (with clitics staying early). Examples:

U parku sam prošli vikend razgovarala s njom.
S njom sam razgovarala u parku prošlog vikenda.

Do I need a comma after Prošli vikend?

No. Croatian normally doesn’t use a comma after a simple fronted time or place expression: Prošli vikend sam… (no comma).

How do I pronounce s njom?

Pronounce nj as the palatal sound like the “ny” in English “canyon.” s njom sounds roughly like [s-nyom]. It’s always written as two words.

How would I ask “Who did you talk with…?” or “Where…?” using this verb?

With whom: S kim si razgovarala prošli vikend u parku? (male speaker: razgovarao)
Where: Gdje si razgovarala s njom prošli vikend?

How do I say what we talked about?

Use o + locative for the topic: Razgovarala sam s njom o poslu/u parku.
Examples: o poslu (about work), o školi (about school), o planovima (about plans).