भाई बाहर है; बहन अंदर है।

Hindi normally does not use articles the way English does. So भाई can mean brother, a brother, or the brother, depending on context. The same is true for बहन.

So:

• भाई बाहर है = Brother is outside / The brother is outside
• बहन अंदर है = Sister is inside / The sister is inside

Context tells you which English version sounds best.

Yes, slightly.

In English, we say:

• Brother is outside

In Hindi, the pattern is:

• भाई बाहर है
• literally: Brother outside is

This is normal in Hindi. The basic structure here is:

• subject + location/state + form of "to be"

So बहन अंदर है follows exactly the same pattern.

है is the present-tense form of to be for a singular third-person subject in this kind of sentence. In this sentence, it means is.

So:

• भाई बाहर है = Brother is outside
• बहन अंदर है = Sister is inside

You will often see other forms too:

• मैं हूँ = I am
• तुम हो = you are
• वे हैं = they are

No. In the present tense, है does not change for gender.

So both of these are correct:

• भाई बाहर है — masculine subject
• बहन अंदर है — feminine subject

What matters here is mainly number/person, not masculine vs. feminine. Since both भाई and बहन are singular, है is used in both clauses.

Not by itself. भाई simply means brother. Depending on context, it might be understood as:

• my brother
• your brother
• the brother
• just brother in a general sense

Hindi often leaves out possessive words when the meaning is already clear from context.

If you want to be explicit, you can say:

• मेरा भाई बाहर है = My brother is outside
• मेरी बहन अंदर है = My sister is inside

Here, बाहर and अंदर are location words meaning outside and inside. In this sentence, they work like predicate complements with है:

• भाई बाहर है = Brother is outside
• बहन अंदर है = Sister is inside

You do not need में here.

If you want to specify inside/outside of something, you can expand the phrase:

• भाई घर के बाहर है = Brother is outside the house
• बहन कमरे के अंदर है = Sister is inside the room

So in this sentence, बाहर and अंदर stand perfectly well on their own.

A rough guide:

• भाई = bhaai
  The first sound is an aspirated b sound (bh), and the end sounds roughly like eye.

• बाहर = baa-har
  Long aa at the start.

• बहन = roughly ba-han or behan depending on accent
  The ह is lightly pronounced.

• अंदर = an-dar

• है = written hai in transliteration
  In actual pronunciation, it often sounds closer to heh/hai than a full English high, depending on accent.

As always, native pronunciation varies a bit by region and speaking style.

The semicolon simply links two short, closely related clauses:

• भाई बाहर है; बहन अंदर है।

It is similar to writing:

• भाई बाहर है, बहन अंदर है।
• भाई बाहर है और बहन अंदर है।
• or even two separate sentences.

So the semicolon is a punctuation choice, not a special grammar feature of Hindi.

Yes. That would be very natural:

• भाई बाहर है और बहन अंदर है।

This means Brother is outside and sister is inside.

The version without और is also fine, especially when the contrast is already clear.

Sometimes, yes, in very casual speech, notes, headlines, or dramatic style, people may say something like:

• भाई बाहर, बहन अंदर।

But for standard, full sentences—especially as a learner—you should keep है:

• भाई बाहर है; बहन अंदर है।

That is the safest and most correct form to learn first.

Then you would usually use हैं instead of है.

Examples:

• भाई बाहर हैं।
  This can mean The brothers are outside or Brother is outside in a respectful sense.

• बहन अंदर हैं।
  This can mean The sisters are inside or respectful Sister is inside, depending on context.

So:

• है = singular, non-honorific
• हैं = plural or honorific/respectful

That is an important pattern in Hindi.