Learn Hardcore Croatian: Ona govori polako jer me razumije. - She speaks slowly because she understands me.

Yes. Croatian is pro‑drop, so Govori polako jer me razumije is perfectly natural. Keeping ona adds emphasis or contrast (e.g., “SHE speaks slowly…”).

Why govori and not priča?

govoriti = to speak (the act of speaking, e.g., speaking a language, speaking slowly)
pričati = to talk, tell (chat, tell stories) Here, govori polako means “speaks slowly,” which fits better than priča polako unless you mean “talks slowly” in a conversational sense.

Why is polako after the verb? Can it go before it?

Both are possible:

Neutral: Govori polako.
Emphasis on the manner: Polako govori (slightly more contrastive/stylistic). Your sentence could also be: Ona polako govori jer me razumije (perfectly fine).

Is there a difference between polako and sporo?

Both can mean “slowly,” but:

polako = slowly in pace; also used like “take it easy/slow down.”
sporo = slow in the sense of being sluggish or inherently slow. For speech, polako is more common/natural; sporo govori can sound like “she’s a slow speaker (by nature).”

Why jer and not zato što?

Both mean “because.”

jer is short, very common, and fine mid‑sentence.
zato što is a bit more explicit and is the safer choice at the start of a sentence: Zato što me razumije, govori polako. Starting with Jer is less typical in Croatian.

Do I need a comma before jer?

Often no. In modern Croatian, when jer introduces a reason that’s integral to the statement, writers commonly omit the comma: Govori polako jer me razumije. A comma may appear when the second part is more explanatory/parenthetical. In short sentences like this, leaving the comma out is a safe default. With zato što, a comma is usually used: …, zato što me razumije.

Why is it me and not mene or mi?

me = unstressed (clitic) form, Acc/Gen; here it’s Accusative (“understands me”).
mene = stressed/long form; used for emphasis or after prepositions (e.g., bez mene).
mi = Dative (“to me”) or Nominative “we.” Since razumjeti takes a direct object, you need Accusative: me (or emphatic mene).

Where does me go in the jer clause? Can I say jer razumije me?

Object clitics like me prefer the second position in their clause. After jer, the default is:

jer me razumije (correct, natural) Avoid jer razumije me in standard Croatian; it sounds non‑native. Without jer, both Razumije me and Ona me razumije are fine.

Can I say jer me ona razumije or jer ona me razumije?

Yes, both are possible, depending on focus:

jer me ona razumije (focus on “me”: it’s ME whom she understands)
jer ona me razumije (focus on “ona”: SHE is the one who understands me) The clitic me must stay in the second position of its clause chunk (after jer or after the first stressed word).

Why is it spelled razumije and not razume or razumje?

Standard Croatian uses the ijekavian pattern: razumjeti → razumije.
razume/razumeti is Serbian (ekavian), not Croatian.
razumje is a misspelling in Croatian; keep ije: razumije.

How do I make it negative? Where does ne go?

Affirmative: … jer me razumije.
Negative: … jer me ne razumije. In clauses that start with jer, the clitic cluster (here me) still wants second position, and ne attaches to the verb: jer me ne razumije (not: ✗ jer ne me razumije).

Does the present tense here mean “speaks” or “is speaking”?

Both. Croatian present covers simple and progressive meanings; context decides. Ona govori polako can mean “She speaks slowly (in general)” or “She is speaking slowly (right now).”

Could I use shvaćati/shvatiti instead of razumjeti?

Sometimes:

razumjeti = to understand (comprehend, understand language/content).
shvaćati (impf.) / shvatiti (pf.) = to grasp/realize. In this sentence about understanding someone’s speech, razumjeti is the natural choice. Shvaća me would be more “she gets me (on a deeper level).”