Sve je dobro sem plana.

Here sve means everything.

It comes from the word sav / sva / sve, which means all or entire. When Serbian uses sve by itself like this, it usually means everything and is treated as grammatically neuter singular.

Because sve in the sense of everything is grammatically singular.

So:

• Sve je dobro = Everything is good
• not Sve su dobro

If the subject were truly plural, you would use su, for example:

• Svi su dobro = Everyone is well
• Planovi su dobri = The plans are good

Because dobro agrees with sve.

Since sve here is treated as neuter singular, the predicate adjective also appears in the neuter singular form:

• dobar = masculine singular
• dobra = feminine singular
• dobro = neuter singular

So Sve je dobro is grammatically built the same way as To je dobro.

Here it is an adjective, not an adverb.

It describes sve: everything is good/fine.

Compare:

• Sve je dobro — dobro is an adjective
• On govori dobro — dobro is an adverb meaning well

This is a very common point of confusion, because the form looks the same.

Sem means except, apart from, or besides.

So sem plana means except for the plan.

It is a normal Serbian word, but many learners will hear osim more often in everyday speech. So this sentence is perfectly understandable and correct, but osim is often the safer everyday alternative.

Because sem is followed by the genitive case.

The noun plan is:

• plan = nominative singular
• plana = genitive singular

So:

• sem plana = except for the plan

This is the same kind of pattern you see with other Serbian words that require the genitive.

Yes. You can say:

• Sve je dobro sem plana.
• Sve je dobro osim plana.

Both are correct and mean essentially the same thing.

A useful learner rule is:

• osim = very common and neutral
• sem = also correct, sometimes a bit more concise, literary, or stylistically marked depending on context and region

It is the same spelling, but not the same function.

• In sve knjige, sve means all and agrees with the plural feminine noun knjige
• In Sve je dobro, sve stands alone and means everything

So even though the word looks identical, the grammar is different.

Yes, but the original order is the most neutral:

• Sve je dobro sem plana.

You may also see:

• Sem plana, sve je dobro.

That version puts more emphasis on sem plana.

For learners, the original sentence is the safest default pattern.

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

So plana by itself can mean:

• the plan
• a plan
• sometimes just plan in a general sense

The exact meaning comes from context. In a sentence like this, English will often use the plan, even though Serbian does not mark that directly.

It can cover all of those, depending on context.

In many everyday situations, Sve je dobro sounds closer to:

• Everything is fine
• Everything is okay

rather than a strong moral judgment like Everything is morally good.

So in this sentence, the natural feel is usually:

• everything is fine/good, except for the plan