Dvojica nose prsluke za spašavanje.

Dvojica is a special numeral used for groups of male people.

So:

• dvojica = two men / two male persons
• dva is the ordinary two, usually used with things, or with a noun like dva muškarca

You can say:

• Dvojica nose prsluke za spašavanje. = Two men are wearing/carrying life jackets.
• Dva muškarca nose prsluke za spašavanje. = also possible

But when the noun is omitted, dvojica is the natural choice if you mean a male pair.

Yes, normally dvojica suggests a male group.

If the group were female, you would usually say something like:

• Dvije žene nose prsluke za spašavanje.

If the group were mixed or of another type, Croatian might use a different form depending on context, such as dvoje in some cases. So dvojica is not just any two — it specifically points to male persons.

Because the subject is dvojica, meaning two people, so the verb agrees in the plural.

• nosi = he/she/it carries, wears
• nose = they carry, wear

So:

• Dvojica nose ... = Two men are carrying/wearing ...

Even though dvojica looks like a single word, it refers to more than one person, so plural agreement is used.

The dictionary form is nositi.

In the present tense:

• nosim = I carry / I wear
• nosiš = you carry / you wear
• nosi = he/she carries / wears
• nosimo = we carry / wear
• nosite = you all carry / wear
• nose = they carry / wear

So nose is the 3rd person plural present tense form.

It can mean both.

That is very common in Croatian:

• nositi torbu = to carry a bag
• nositi kaput = to wear a coat

So Dvojica nose prsluke za spašavanje can, in principle, mean either:

• they are wearing life jackets, or
• they are carrying life jackets

Usually the context tells you which meaning is intended.

Because prsluke is the accusative plural form, used here for the direct object.

The noun is:

• prsluk = vest / jacket

Its relevant forms are:

• prsluk = singular
• prsluci = nominative plural
• prsluke = accusative plural

Since the sentence is talking about more than one life jacket as the thing being worn/carried, Croatian uses prsluke.

So:

• nose prsluke = they wear/carry vests

Because together the two people have more than one life jacket, so Croatian naturally uses the plural.

This works much like English:

• They are wearing life jackets.

Even if each person has one, the total number is plural, so prsluke is completely normal.

Literally, it means for rescuing / for спасavanje / for saving.

Here:

• za = for
• spašavanje = rescuing, saving, rescue

So:

• prsluk za spašavanje = a life jacket / rescue vest
• literally: a vest for saving/rescue

This is a very common Croatian way to build compound meanings: a noun + za + another noun or verbal noun.

Because za normally takes the accusative, but spašavanje is a neuter noun whose nominative and accusative singular forms are the same.

So you do not see a visible change here.

Compare the idea:

• nominative: spašavanje
• accusative: spašavanje

That is why after za it still appears as spašavanje.

Because Croatian does not use articles like English does.

So:

• prsluke can mean life jackets, the life jackets, or sometimes just be understood from context
• Dvojica can mean two men, the two men, etc.

Croatian relies on context, word order, and situation instead of articles.

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

The neutral order here is:

• Dvojica nose prsluke za spašavanje.

But other orders are possible for emphasis, for example:

• Prsluke za spašavanje nose dvojica.
• Nose prsluke za spašavanje dvojica.

These all keep roughly the same core meaning, but the emphasis changes. English usually has to stay much closer to a fixed word order.

You can do that. Common options include:

• Dvojica muškaraca nose prsluke za spašavanje.
• Dva muškarca nose prsluke za spašavanje.

Both are possible, but they are built differently:

• dvojica muškaraca uses the special male-person numeral
• dva muškarca uses the ordinary numeral dva

When the noun is omitted, dvojica by itself is especially useful.