Tarifa i iznos su na računu.

Because together they form a compound subject: tarifa i iznos = the tariff/rate and the amount.

Even though each noun is singular by itself, the whole subject is plural, so Serbian uses the plural form of to be:

• je = is
• su = are

So:

• Tarifa je na računu. = The tariff/rate is on the bill.
• Iznos je na računu. = The amount is on the bill.
• Tarifa i iznos su na računu. = The tariff/rate and the amount are on the bill.

They are in the nominative case, because they are the subject of the sentence.

The subject is the thing that is somewhere:

• tarifa = the tariff/rate
• iznos = the amount

Since they are the ones being talked about, they stay in nominative:

• tarifa
• iznos

Because after na when it means location (on, in, at), Serbian uses the locative case.

So:

• račun = nominative/base form
• na računu = on the bill / on the invoice / on the account

Compare the general pattern:

• na stolu = on the table
• na slici = in the picture / on the picture
• na računu = on the bill/invoice/account

If na expresses movement toward something, it usually takes the accusative. But here there is no movement; it is just location.

Računu is the locative singular form of račun.

The noun račun is masculine, and in this sentence it changes because it comes after na in a location meaning.

So:

• račun = account / bill / invoice / check / calculation
• na računu = on the account / on the bill / on the invoice

This kind of ending is very common for masculine nouns in the locative singular.

Because Serbian often uses na with things like documents, pages, surfaces, lists, screens, and similar contexts where English may say on or sometimes even in.

So na računu is the natural Serbian expression for something being on the bill/invoice/account statement.

Some useful comparisons:

• na papiru = on the paper
• na stranici = on the page
• na ekranu = on the screen
• na računu = on the bill / on the account

Using u računu would usually not sound natural in this meaning.

Serbian has no articles like English a/an/the.

So:

• tarifa can mean a tariff, the tariff
• iznos can mean an amount, the amount
• račun can mean a bill, the bill, depending on context

In real use, context tells you whether English should use a or the.

So Tarifa i iznos su na računu could be understood as:

• The tariff and the amount are on the bill
• or, depending on context, A tariff and an amount are on the bill

But in most practical situations, English would probably use the.

No. Račun is a very common Serbian word with several meanings depending on context. It can mean:

• bill
• invoice
• check (in a restaurant)
• account
• calculation

So na računu could mean different things depending on the situation:

• on the bill
• on the invoice
• on the account statement
• in the account balance context

That is why context matters a lot with račun.

They are related, but not the same.

• tarifa = the rate, tariff, pricing category, or plan
• iznos = the amount, usually the numerical sum of money

So in a bill or invoice context:

• tarifa may refer to the type of charge or rate
• iznos is the actual amount charged

For example, one is more like the pricing label or rate, and the other is the sum.

Yes. Serbian word order is more flexible than English word order.

The neutral order here is:

• Tarifa i iznos su na računu.

But depending on emphasis, you could also hear:

• Na računu su tarifa i iznos.

That version puts more focus on where they are: On the bill are the tariff and the amount.

Even though word order can change, the cases and verb form help show what the sentence means.

In a full standard sentence like this, su is normally kept.

• Tarifa i iznos su na računu. = full sentence

Without su:

• Tarifa i iznos na računu

this sounds more like a heading, note, label, or incomplete phrase, not a normal complete sentence.

So if you want a regular statement, keep su.

Because Serbian usually does not need subject pronouns when the subject is already clearly stated.

The subject is already present:

• Tarifa i iznos

So adding oni would be unnecessary.

Serbian often omits pronouns unless they are needed for contrast or emphasis.

Yes, they have grammatical gender:

• tarifa = feminine
• iznos = masculine
• račun = masculine

In this sentence, gender matters less than number, because the verb agrees with the whole subject tarifa i iznos, which is plural.

That is why the verb is su, regardless of the fact that one noun is feminine and the other is masculine.

It would be:

Тарифа и износ су на рачуну.

Serbian normally uses both scripts, Latin and Cyrillic, and this sentence means the same in either one.

Letter-by-letter here:

• Tarifa → Тарифа
• i → и
• iznos → износ
• su → су
• na računu → на рачуну

A simple English-friendly approximation is:

RAH-choo-noo

More carefully:

• č sounds like ch in church
• u is like oo in food

So:

• račun ≈ RAH-choon
• računu ≈ RAH-choo-noo

Also, r in Serbian is rolled or tapped more than in standard English.

Yes. I is the basic Serbian word for and.

So:

• tarifa i iznos = tariff/rate and amount

It is one of the most common words in the language. Be careful not to confuse it with English I; in Serbian, i is a conjunction, not a pronoun.