Questions & Answers about Ne znam koliko košta ova haljina.
Because znam is the present tense of znati (to know), and in Serbian you usually negate present-tense verbs by putting ne in front of them:
- znam = I know
- ne znam = I don’t know
Nisam is the negative form of sam (I am / I have as an auxiliary), so it is used with past forms, not with a simple present verb like znam.
Here koliko means how much.
In this sentence, it introduces an indirect question:
- Koliko košta ova haljina? = How much does this dress cost?
- Ne znam koliko košta ova haljina. = I don’t know how much this dress costs.
So koliko can mean how much or how many, depending on context.