Learn Croatian: Tko je ova žena?

ova is the feminine form of the word for this. In Croatian, demonstrative pronouns must match the gender of the noun they point to. Since žena (woman) is a feminine noun, we must use the feminine form ova. You would use ovaj for a masculine noun and ovo for a neuter noun.

Why is the verb je placed right after Tko?

je is a clitic, which means it is a short, unstressed word. A major rule in Croatian is that clitics must almost always go in the second position in a sentence. Because Tko is the first word, je naturally falls into its required second spot.

Could I change the word order to Ova žena je tko?

It would sound very unnatural. In Croatian, question words like Tko (who) generally need to be at the very beginning of the sentence. Starting with Tko also perfectly sets up the second position for the clitic je.

How do I pronounce the first letter of žena?

The letter ž (with the little v-shaped mark on top) sounds like the s in the English word measure or pleasure. It is not pronounced like a regular English z.