Biram ribu sa spiska.

Biram is the 1st person singular present tense form of the verb birati.

• birati = to choose
• biram = I choose / I am choosing

Serbian dictionaries usually give the infinitive form, so learners often first see birati, but in an actual sentence you usually need a conjugated form like biram.

It is understood from the verb form.

In Serbian, subject pronouns are often omitted when they are clear from the verb:

• biram already means I choose
• so ja biram is possible, but ja is often unnecessary

You would add ja only if you want emphasis or contrast:

• Ja biram ribu, a on bira meso.
  I’m choosing fish, and he’s choosing meat.

Because it is in the accusative case, which is used for the direct object of the verb.

Here, the thing being chosen is fish, so riba changes to ribu.

For many feminine nouns ending in -a:

• nominative singular: riba
• accusative singular: ribu

So:

• Riba je sveža. = The fish is fresh.
  Here riba is the subject.
• Biram ribu. = I choose fish.
  Here ribu is the object.

Because after sa in this sentence, the noun goes into the genitive case.

• base form: spisak = list
• genitive singular: spiska

So:

• spisak = the list
• sa spiska = from the list / off the list

This is a very common pattern in Serbian.

Yes, sa can mean with, but it can also mean from/off, depending on context.

In Biram ribu sa spiska, sa means from/off:

• sa stola = from the table / off the table
• sa spiska = from the list / off the list

So this is not with the list. It means the fish is being selected from the items on the list.

Because Serbian normally uses sa spiska for the idea from/off a list.

A list is often treated conceptually like a surface or set of listed items, so sa sounds natural here.

• sa spiska = from the list / off the list

Using iz here would usually sound unnatural in standard usage.

Biram comes from birati, which is imperfective.

That means it can describe:

• an ongoing action
• a repeated action
• the general process of choosing

So Biram ribu sa spiska can mean:

• I’m choosing fish from the list
• I choose fish from the list, depending on context

If you want to express a completed choice, Serbian often uses a perfective verb such as izabrati:

• Izabrao sam ribu sa spiska. = I chose / have chosen the fish from the list.

Yes. Serbian word order is fairly flexible, although some orders are more neutral than others.

The neutral order here is:

• Biram ribu sa spiska.

But you could also say:

• Ribu biram sa spiska.
• Sa spiska biram ribu.

These versions shift the focus or emphasis:

• Ribu biram... emphasizes fish
• Sa spiska biram... emphasizes from the list

So the original sentence is the most straightforward, neutral version.

It is singular.

• riba = fish
• ribu = fish in the accusative singular

The plural would be different:

• nominative plural: ribe
• accusative plural: ribe

So:

• Biram ribu. = I’m choosing one fish / fish as a singular item
• Biram ribe. = I’m choosing fish (plural)

No, Serbian does not have articles like English a/an/the.

So Biram ribu sa spiska does not explicitly say:

• I choose a fish from the list or
• I choose the fish from the list

That kind of definiteness is usually understood from context.

Not usually, unless you really mean a list in a general sense.

• spisak = list
• jelovnik or meni = menu

So if you are choosing fish from a restaurant menu, a more natural sentence might be:

• Biram ribu sa jelovnika.
• Biram ribu sa menija.

But sa spiska is perfectly fine if the context is literally a list, such as a shopping list, options list, inventory list, or similar.

A simple approximate pronunciation for an English speaker is:

BEE-ram REE-boo sa SPEE-ska

A few helpful notes:

• r in Serbian is trilled or tapped
• i is like the ee in see
• u is like oo in food
• a is like a in father

Serbian spelling is very regular, so once you know the sound system, pronunciation becomes much easier.