Podnosilac bira poštansku dostavu.

Podnosilac is an administrative/legal word meaning applicant, submitter, or the person who files something such as a request, application, or claim.

It comes from the verb podneti / podnositi = to submit / to file.

In official Serbian, podnosilac is very common in formal documents.

Bira is the 3rd person singular present tense of birati = to choose / to select.

So:

• ja biram = I choose
• ti biraš = you choose
• on/ona bira = he/she chooses
• podnosilac bira = the applicant chooses

In forms and official instructions, Serbian often uses the present tense this way to state what someone does in the procedure.

Because this phrase is the direct object of bira.

The basic form is:

• poštanska dostava = postal delivery / mail delivery

But after a verb like bira when it is the thing being chosen, it goes into the accusative case:

• poštanska dostava → poštansku dostavu

Both words change because:

• dostava is a feminine noun
• poštanska is an adjective that must agree with it

So:

• nominative: poštanska dostava
• accusative: poštansku dostavu

It is accusative singular feminine.

Breakdown:

• poštansku = accusative singular feminine of poštanski
• dostavu = accusative singular of dostava

This is very common in Serbian when a feminine noun is the direct object:

• vidim kuću = I see the house
• imam knjigu = I have a book
• biram dostavu = I choose delivery

Poštansku means postal or by mail.

Its dictionary form is poštanski. It is an adjective built from pošta = post office / mail.

Because it describes dostavu and must match its gender, number, and case, it appears here as poštansku.

So:

• poštanski = postal
• poštanska usluga = postal service
• poštansku dostavu = postal delivery

Because Serbian has no articles.

English says things like:

• the applicant
• an applicant
• postal delivery
• the postal delivery

Serbian usually leaves that information to context. So Podnosilac bira poštansku dostavu can be translated depending on context as:

• The applicant chooses postal delivery
• An applicant chooses postal delivery
• The applicant selects delivery by mail

No, Serbian word order is fairly flexible, although the version you have is the most neutral and natural in official style:

• Podnosilac bira poštansku dostavu.

Other orders are possible, but they change emphasis:

• Poštansku dostavu bira podnosilac.
  Emphasizes poštansku dostavu or sounds contrastive.

• Podnosilac poštansku dostavu bira.
  Possible, but less neutral.

So for a simple statement, subject + verb + object is the best default.

Yes. Birati is the imperfective verb: to choose / to be choosing / to choose in a general sense.

Its perfective partner is izabrati: to choose / to select once, to make the choice.

In administrative language, birati in the present tense is very natural because it describes the action as part of a procedure:

• Podnosilac bira poštansku dostavu. = The applicant chooses postal delivery.

If you used izabrati, you would normally need a different tense or structure, for example:

• Podnosilac je izabrao poštansku dostavu. = The applicant has chosen / chose postal delivery.
• Podnosilac će izabrati poštansku dostavu. = The applicant will choose postal delivery.

Yes, absolutely.

A very natural alternative is:

• Podnosilac bira dostavu poštom.

That literally means The applicant chooses delivery by mail.

The difference is mostly stylistic:

• poštanska dostava sounds a bit more like a fixed administrative term
• dostava poštom is slightly more transparent and everyday

Both are correct and natural.

A rough pronunciation guide:

• podnosilac ≈ pod-no-see-lats
• poštansku ≈ posh-tahn-skoo
• dostavu ≈ dos-tah-voo

A few useful letter notes:

• š sounds like sh in ship
• c sounds like ts in cats
• u is always like oo in food

So poštansku has the sh sound, and podnosilac ends with ts, not k or s.

Grammatically, podnosilac is a masculine noun, but in official Serbian it is often used in a generic administrative sense, similar to many formal job or role nouns.

So in legal or bureaucratic language, it can refer to the applicant as a role, not necessarily to a male person specifically.

This is common in official documents and forms.