Sterilizacija i kastracija su besplatne.

Su is the 3rd person plural present tense of biti (to be).

So:

• sterilizacija = sterilization
• kastracija = castration
• su = are
• besplatne = free

Because there are two things joined by i (and), the subject is plural, so Croatian uses su = are.

Because the subject is made of two nouns:

• sterilizacija
• kastracija

Together they form a plural subject, so the adjective must also be plural.

Compare:

• Sterilizacija je besplatna. = Sterilization is free.
• Kastracija je besplatna. = Castration is free.
• Sterilizacija i kastracija su besplatne. = Sterilization and castration are free.

So the adjective changes from besplatna (singular feminine) to besplatne (plural, agreeing with feminine nouns).

Croatian adjectives must agree with the nouns they describe in gender, number, and case.

Both nouns here are feminine singular:

• sterilizacija – feminine
• kastracija – feminine

When two feminine nouns are joined, the adjective is typically feminine plural, so:

• besplatne = feminine plural

If the plural group were masculine, you would usually get besplatni instead.

A very common clue in Croatian is the ending -a. Many nouns ending in -a are feminine.

So:

• sterilizacija → feminine
• kastracija → feminine

That is why you get:

• je besplatna in singular
• su besplatne in plural

As always, there are exceptions elsewhere in the language, but in this sentence these two nouns are feminine.

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

The basic structure is:

• Sterilizacija i kastracija = the subject
• su = the verb
• besplatne = predicate adjective

So this is a straightforward nominative subject sentence.

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

So:

• Sterilizacija can mean sterilization or the sterilization, depending on context.
• Kastracija can mean castration or the castration.
• Sterilizacija i kastracija su besplatne. naturally means Sterilization and castration are free or The sterilization and castration are free, depending on the situation.

Context tells you whether the meaning is general or specific.

In standard Croatian, su is normally kept in this kind of sentence.

So the normal sentence is:

• Sterilizacija i kastracija su besplatne.

You generally should not omit su here.

Croatian sometimes allows different styles or shortened expressions in headlines, ads, or very informal language, but for a learner, the correct full sentence is with su.

Yes. Croatian word order is fairly flexible because endings carry a lot of grammatical information.

The most neutral order here is:

• Sterilizacija i kastracija su besplatne.

But you could also see:

• Besplatne su sterilizacija i kastracija.

That version puts more emphasis on besplatne (free).

Still, the original sentence is the most natural and straightforward version for most contexts.

Yes, in this sentence i means and.

So:

• sterilizacija i kastracija = sterilization and castration

It is the normal Croatian coordinating conjunction for joining words or phrases.

In this exact form, yes: besplatne is the form used here because it agrees with a feminine plural subject.

Related forms include:

• besplatan – masculine singular
• besplatna – feminine singular
• besplatno – neuter singular
• besplatni / besplatne / besplatna – plural forms depending on gender pattern and usage

For this sentence, the important contrast is:

• besplatna = singular feminine
• besplatne = plural feminine

A simple approximate pronunciation is:

Ste-ri-li-ZA-tsi-ya i kas-TRA-tsi-ya su bes-PLAT-ne

A few useful notes:

• c in Croatian is like ts in cats
• j is like English y in yes
• stress is not usually marked in normal writing, so learners often just imitate native speech at first

So:

• sterilizacija ≈ sterilizatsiya
• kastracija ≈ kastratsiya
• besplatne ≈ besplatne with a clear t and n

In everyday use, they are related but not always identical terms.

Very broadly:

• sterilizacija refers to sterilization
• kastracija refers to castration/neutering

In veterinary and everyday public information, the exact English translation may vary by context, and sometimes English uses spaying/neutering where Croatian uses these terms.

So grammatically they are just two feminine nouns joined together, but semantically they refer to related medical/veterinary procedures.

You would use the singular verb and singular adjective.

For example:

• Sterilizacija je besplatna.
• Kastracija je besplatna.

Changes:

• su → je (are → is)
• besplatne → besplatna (plural feminine → singular feminine)

So the plural forms in the original sentence are there only because there are two coordinated nouns.