Serviser će zameniti matičnu ploču osim ako nedostaje rezervni deo.

This is the Serbian Future I tense.

It is usually formed with:

• a form of hteti used as an auxiliary: ću, ćeš, će, ćemo, ćete, će
• plus the infinitive

So:

• Serviser će zameniti = The technician will replace

Here, će is the 3rd person singular form, because serviser is singular.

You may also see:

• Serviser zameniće... in older or more literary style
• Zameniće... as a one-word future form
• Serviser će da zameni... in colloquial speech

But će zameniti is completely normal and standard.

Because će is a clitic. In Serbian, clitics usually go in the second position of the clause, after the first stressed element.

So:

• Serviser će zameniti matičnu ploču.

This is very natural Serbian word order.

A literal English-speaking learner might expect something like Serviser zameniti će, but that is not how clitics normally work.

You can also say:

• Zameniće matičnu ploču. = He/She will replace the motherboard.

So the position of će is about Serbian sentence structure, not about emphasis on the future.

Because it is the direct object of the verb zameniti.

The verb zameniti takes the accusative case, so matična ploča changes form:

• nominative: matična ploča
• accusative: matičnu ploču

Both the adjective and the noun change:

• matična → matičnu
• ploča → ploču

So:

• Serviser će zameniti matičnu ploču. = The technician will replace the motherboard.

Rezervni deo is in the nominative singular.

That is because it is the subject of nedostaje.

In Serbian, with nedostajati / nedostaje, the thing that is missing is usually the grammatical subject:

• Rezervni deo nedostaje. = A spare part is missing.

So in your sentence:

• osim ako nedostaje rezervni deo = unless a spare part is missing

English speakers sometimes expect it to behave like to lack or to not have, but Serbian structures it differently here.

Compare:

• Nedostaje rezervni deo. = A spare part is missing.
• Nema rezervnog dela. = There is no spare part.

Those are related in meaning, but the grammar is different.

Because after expressions like osim ako (unless), Serbian often uses the present tense to express a condition connected to the future.

This is similar to English:

• The technician will replace it unless a spare part is missing.

In English, you also normally say is missing, not will be missing, after unless.

So:

• će zameniti = future main action
• osim ako nedostaje... = present-tense condition

This is normal Serbian usage.

Osim ako means unless.

Literally, it is close to except if:

• osim = except
• ako = if

So:

• Serviser će zameniti matičnu ploču osim ako nedostaje rezervni deo. = The technician will replace the motherboard unless a spare part is missing.

It introduces an exception to what is stated in the main clause.

Sometimes yes, but not always in exactly the same way.

For unless, Serbian often prefers osim ako in clearer, more standard phrasing:

• ...osim ako nedostaje rezervni deo.

A sentence with ako ne would usually need a different structure, for example:

• Serviser će zameniti matičnu ploču ako ne nedostaje rezervni deo is not natural.

You would more naturally reformulate:

• Serviser će zameniti matičnu ploču ako rezervni deo ne nedostaje — grammatically possible, but awkward
• better: ...ako ima rezervnog dela = if there is a spare part
• or simply keep osim ako

So for this sentence, osim ako is the best choice.

No. Serbian does not have articles like English the and a/an.

So:

• serviser can mean a technician or the technician
• matična ploča can mean a motherboard or the motherboard
• rezervni deo can mean a spare part or the spare part

The exact meaning depends on context.

That is why one Serbian sentence can be translated into English in more than one way depending on the situation.

Serviser usually means a technician, repair person, or service technician.

It is a common word in Serbian for someone who repairs or services equipment, machines, electronics, appliances, and similar things.

So in this sentence, serviser is the person doing the replacement.

Yes. Matična ploča is the standard Serbian term for motherboard.

Word-for-word, it looks like:

• matična = literally something like main / mother-related
• ploča = board / plate

In computer context, matična ploča is exactly the normal expression for the main circuit board in a computer.

This sentence has both sounds, and English speakers often find them tricky.

• č as in matičnu, ploču is a harder sound, roughly like ch in church
• ć as in će is a softer sound, made farther forward in the mouth

So:

• č = harder ch
• ć = softer, more palatal sound

If you pronounce both the same at first, people will usually still understand you, but learning the difference will make your Serbian sound much more natural.

Yes. Serbian word order is flexible, although not completely free.

For example, you could also say:

• Osim ako nedostaje rezervni deo, serviser će zameniti matičnu ploču.

This puts the condition first:

• Unless a spare part is missing, the technician will replace the motherboard.

The meaning stays basically the same, but the emphasis changes slightly.

What you should still watch carefully is the placement of clitics like će, which must follow normal Serbian clitic rules.