Krvni pritisak i telesna težina su u obrascu.

Because the subject is two things joined by i (and):

• krvni pritisak = blood pressure
• telesna težina = body weight

Together they form a plural subject, so Serbian uses the 3rd person plural form of biti (to be):

• je = is
• su = are

So:

• Krvni pritisak je u obrascu. = Blood pressure is in/on the form.
• Krvni pritisak i telesna težina su u obrascu. = Blood pressure and body weight are in/on the form.

Because adjectives in Serbian must agree with the noun they describe in gender, number, and case.

Here:

• pritisak is masculine singular, so the adjective is krvni
• težina is feminine singular, so the adjective is telesna

So the pairs are:

• krvni pritisak = masculine singular
• telesna težina = feminine singular

This kind of agreement is completely normal in Serbian.

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

You can tell this from their dictionary-like basic forms:

• pritisak
• težina

The nominative is typically the case used for the subject of a sentence.

Because the preposition u can take different cases depending on meaning.

Here it means in / on the form, indicating location, so u takes the locative case.

• nominative: obrazac = form
• locative: obrascu = in/on the form

So:

• u obrascu = in the form / on the form

If u expresses movement into something, then it often takes the accusative instead. But here nothing is moving; the information is simply located there.

Obrascu is the locative singular form of obrazac, which means form.

Case change:

• obrazac = form
• u obrascu = in/on the form

So the ending changes because the noun follows the preposition u in a location meaning.

Because Serbian does not have articles like English a/an and the.

So Serbian simply says:

• Krvni pritisak i telesna težina su u obrascu.

Depending on context, that could correspond to English:

• Blood pressure and body weight are in the form
• The blood pressure and body weight are on the form
• Blood pressure and body weight are included in the form

English needs articles; Serbian usually does not.

Literally, u obrascu is in the form.

But in natural English, depending on context, it may be translated as:

• on the form
• in the form
• included in the form

Serbian often uses u where English might prefer on with documents, forms, lists, and similar contexts.

So even if the literal wording is in the form, the natural English translation may be on the form.

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

The neutral order here is:

• Krvni pritisak i telesna težina su u obrascu.

But other orders are possible, for example:

• U obrascu su krvni pritisak i telesna težina.

That version puts more focus on where they are.

Even though word order can change, the original sentence is a very normal, neutral way to say it.

Yes. I is the standard Serbian word for and.

So:

• krvni pritisak i telesna težina = blood pressure and body weight

It simply joins the two noun phrases into one coordinated subject.

Because težina is a normal singular noun meaning weight.

Likewise:

• pritisak = pressure

In this sentence, each item is a singular concept:

• blood pressure
• body weight

The sentence becomes plural only because there are two separate items together.

It is two words:

• krvni = blood-related / blood
• pritisak = pressure

Together they mean blood pressure.

This is very common in Serbian: what English may treat as a fixed medical term can often be expressed as an adjective + noun phrase.

Yes, telesna težina is a normal Serbian expression for body weight.

It is built from:

• telesna = bodily / body-related
• težina = weight

So literally it is something like bodily weight, but the natural English equivalent is body weight.

In Serbian Cyrillic, it is:

• Крвни притисак и телесна тежина су у обрасцу.

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

No, not naturally in this kind of sentence.

Serbian often omits subject pronouns because the verb ending already shows the person:

• Ja sam → often just sam in context? not usually alone, but the pronoun ja can be omitted.

But the verb to be in a present-tense sentence like this is normally kept:

• Krvni pritisak i telesna težina su u obrascu.

Leaving out su would sound incomplete or ungrammatical in standard Serbian.