שניהם כבר בבית, אבל אני עוד במשרד.

Because Hebrew usually leaves out to be in the present tense.

So instead of saying something like They are already at home, Hebrew simply says:

שניהם כבר בבית
literally: both of them already at-home

The same thing happens in the second half:

אני עוד במשרד
literally: I still in-the-office

If you wanted past or future, Hebrew would use forms of להיות (to be), but not normally in the present.

שניהם means both of them.

It refers to two people or things that have already been mentioned or are understood from context. It is masculine, or used for a mixed-gender pair.

• שניהם = both of them, masculine / mixed
• שתיהן = both of them, feminine

So if the sentence is talking about two men, or a man and a woman, שניהם is correct.

Because שניהם already includes the idea of they.

It does not mean just two. It means the two of them / both of them.

So:

• הם בבית = they are at home
• שניהם בבית = both of them are at home

Hebrew often uses this kind of compact form instead of adding an extra pronoun.

They create a contrast:

• כבר = already
• עוד = still

So the sentence contrasts their situation with the speaker’s situation:

• שניהם כבר בבית = both of them are already home
• אבל אני עוד במשרד = but I’m still at the office

This is a very natural pairing in Hebrew: כבר ... אבל ... עוד ...

It can mean several things, depending on context.

Common meanings of עוד include:

• still
• more / another
• again / further

In this sentence, it clearly means still.

For example:

• אני עוד כאן = I’m still here
• אני רוצה עוד קפה = I want more coffee

So learners need to pay attention to context.

Because the preposition ב־ (in / at) is attached directly to the noun.

So:

• ב + בית → בבית
• ב + משרד → במשרד

This is normal in Hebrew. Short prepositions like ב־, ל־, and כ־ usually attach to the following word.

Because when ב־ combines with the definite article ה־ (the), Hebrew contracts them.

So:

• ב + ה + בית → בבית
• ב + ה + משרד → במשרד

Even though the ה is not written separately here, the noun is still definite:

• בבית = in the house / at home
• במשרד = in the office

This contraction is very common in Hebrew.

It can mean either one, depending on context.

In many everyday sentences, בבית is best understood as at home.

So here, שניהם כבר בבית most naturally means both of them are already home.

If the context were more physical or descriptive, it could also mean in the house.

In this sentence, במשרד is understood as in the office / at the office, usually meaning a specific office relevant to the speaker.

Hebrew often uses the definite form in places where English may or may not use the.

So אני עוד במשרד sounds very natural for I’m still at the office or I’m still in the office.

Yes. אבל is the standard, very common word for but in Hebrew.

It is used in both speech and writing.

Example:

• רציתי לבוא, אבל הייתי עסוק = I wanted to come, but I was busy

So in this sentence, אבל simply introduces the contrast between them and me.

The word order is natural, but not completely fixed.

The given sentence:

שניהם כבר בבית, אבל אני עוד במשרד.

puts the focus first on both of them, and then contrasts that with me.

You could also say:

אני עוד במשרד, אבל שניהם כבר בבית.

That would shift the emphasis a bit, starting from the speaker instead.

Hebrew allows some flexibility in word order, especially for emphasis and rhythm.

A common pronunciation would be:

shneihem kvar babayit, aval ani od bamisrad

A few notes:

• שניהם = shneihem
• כבר = kvar
• בבית = babayit
• אבל = aval
• אני = ani
• עוד = od
• במשרד = bamisrad

In everyday Israeli speech, this flows quite naturally as one contrastive sentence.

Yes. עדיין also means still, and in this sentence it would work well:

שניהם כבר בבית, אבל אני עדיין במשרד.

That is also perfectly natural.

The difference is mostly one of style and tone:

• עוד is very common and conversational
• עדיין can sound a bit more explicit or slightly more formal

In everyday speech, many speakers would naturally use עוד exactly as in your sentence.