אני במשרד עד 4.

In Hebrew, the verb to be is usually not expressed in the present tense.

So:

• אני במשרד literally looks like I in the office
• but it means I am in the office

This is very normal Hebrew.
In the past or future, Hebrew does use a form of to be, for example:

• הייתי במשרד = I was in the office
• אהיה במשרד = I will be in the office

אני means I.

In this sentence, it is the subject, so it tells you who is in the office. Because there is no present-tense am, keeping אני makes the sentence clear and complete.

In very casual speech or text, Hebrew sometimes drops subject pronouns if the meaning is obvious from context, but אני במשרד עד 4 is the normal full version.

Because ב־ is a prefix meaning in / at, and in Hebrew many prepositions attach directly to the following word.

So:

• ב־ = in / at
• משרד = office
• במשרד = in the office / at the office

This is standard Hebrew spelling.
The same thing happens with other short prepositions too.

In normal unpointed Hebrew spelling, במשרד can represent either one, and context tells you which meaning is intended.

If the meaning shown to the learner is in the office, then the pronunciation is:

• ba-misrad

If it were in an office, it would be pronounced:

• be-misrad

But in everyday writing, both are usually written the same way: במשרד.

Hebrew ב־ covers a wider range than English in alone.

With places, it can often correspond to:

• in
• at

So במשרד may be translated naturally as either:

• in the office
• at the office

English chooses the version that sounds most natural in context.

עד means until or up to.

In this sentence:

• עד 4 = until 4

So it gives the time limit: the speaker is in the office until that time.

Usually, no.

Hebrew commonly uses just the number:

• עד 4
• עד ארבע

Both naturally mean until 4 o’clock if the context is time.

If you want to be more explicit, you can say something like:

• עד השעה 4
• עד השעה ארבע

But in everyday speech, just the number is very common.

When telling time, Hebrew uses the form ארבע.

So:

• עד ארבע = until four

Learners often notice that Hebrew has different number forms, but for clock time, ארבע is the form you want here, not ארבעה.

If the intended meaning is I’m in the office until 4, a natural pronunciation is:

ani ba-misrad ad arba

A rough stress guide:

• a-NI
• ba-mis-RAD
• ad AR-ba

If the meaning were in an office rather than in the office, the middle part would sound like be-misrad instead of ba-misrad.

Yes, Hebrew word order is somewhat flexible, but אני במשרד עד 4 is a very natural, neutral order.

It is basically:

• אני = subject
• במשרד = place
• עד 4 = time limit

You could move things around for emphasis, for example:

• עד 4 אני במשרד

That would put more emphasis on until 4.
But the original sentence is the plain, standard way to say it.

Yes. Very normal.

Modern Hebrew often mixes Hebrew words with Arabic numerals, especially for:

• times
• dates
• prices
• addresses

So אני במשרד עד 4 looks completely natural.
You could also write ארבע, but the digit 4 is common and idiomatic.