Copiii sunt afară.

Because copiii = copii + the definite article -i.

• copil = child
• copii = children
• copiii = the children

So the three i's come from:

1. the stem/plural form ending in -i
2. another i in the plural
3. the definite article -i

This is normal in Romanian, even if it looks unusual to English speakers.

It is pronounced roughly ko-PII-ee.

A helpful way to think of it:

• co = like co in coffee, but shorter
• pii = like pee
• final i = a short ee sound

So the three written i's are not all merged into one long vowel in careful speech. You will usually hear something close to co-PII-i / koˈpi.i.

The basic dictionary form is copil, meaning child.

Here is the pattern:

• copil = child
• un copil = a child
• copii = children
• copiii = the children

Romanian often adds the definite article to the end of the noun instead of putting a separate word like the in front.

Because the subject is plural.

• copiii = the children = plural
• so the verb must also be plural

With the verb a fi (to be):

• este / e = is for singular
• sunt = are for plural

So:

• Copilul este afară. = The child is outside.
• Copiii sunt afară. = The children are outside.

Normally, no. In standard Romanian, you usually need sunt here.

So:

• correct: Copiii sunt afară.
• not standard as a full neutral sentence: Copiii afară.

In very informal speech, people may drop words in context, but for learners, it is best to keep sunt.

Afară usually means outside or outdoors.

In this sentence, Copiii sunt afară, it means:

• The children are outside
• or The children are outdoors

It often refers to location:

• Sunt afară. = I am outside.
• Câinele e afară. = The dog is outside.

Not exactly.

• afară = outside
• în afară can mean outside of, except for, or be part of longer expressions depending on context

Examples:

• Copiii sunt afară. = The children are outside.
• În afară de Maria, toți au venit. = Except for Maria, everyone came.

So in your sentence, the simple word afară is the natural choice.

Because Romanian usually puts the definite article at the end of the noun.

In English:

• the child
• the children

In Romanian:

• copilul = the child
• copiii = the children

So the idea of the is already built into copiii.

Yes, but Copiii sunt afară is the most neutral and natural order.

You may also hear:

• Afară sunt copiii.

This can sound more marked or context-driven, as if you are emphasizing outside or answering a question like Where are the children?

For learners, use:

• Copiii sunt afară.

No. Romanian usually does not need a subject pronoun when the subject noun is already there.

• Copiii sunt afară. = The children are outside.

Adding ei would usually be unnecessary here:

• Ei, copiii, sunt afară could be used for emphasis or contrast, but it is not the normal basic sentence.

Romanian often leaves out subject pronouns unless they are needed for emphasis, contrast, or clarity.

In the singular, you would say:

• Copilul este afară. or more conversationally:
• Copilul e afară.

This means The child is outside.

Compare:

• copilul = the child
• copiii = the children
• este / e = is
• sunt = are

Yes, sunt is the standard present-tense form for they are.

Examples:

• Ei sunt aici. = They are here.
• Copiii sunt afară. = The children are outside.

It is also the form for we are:

• Noi sunt is incorrect
• Noi suntem = We are

So be careful:

• eu sunt = I am
• ei/ele sunt = they are
• noi suntem = we are

A natural stress pattern is:

• co-PII-i for copiii
• SUNT
• a-FA-ră

So roughly:

• co-PII-i sunt a-FA-ră

The strongest sentence stress may fall on afară if you are emphasizing location:

• Copiii sunt afară.

That would sound like: The children are outside, especially if someone is asking where they are.