Ben ofiste çalışırken arkadaşım markette alışveriş yapıyor.

Yes, it often can be omitted in Turkish.

Turkish frequently drops subject pronouns when the person is already clear from context. However, in this sentence, ben is useful because:

• çalışırken does not clearly show I by itself
• the sentence contrasts me with my friend
• saying ben makes that contrast more explicit

So:

• Ben ofiste çalışırken arkadaşım markette alışveriş yapıyor. = very clear, slightly contrastive
• Ofiste çalışırken arkadaşım markette alışveriş yapıyor. = also possible if the context already makes it clear that I am the one working

Çalışırken means while working or when working.

The key part is -ken, which creates a while/when clause. It connects one action to another and shows that they happen at the same time.

So:

• çalışmak = to work
• çalışırken = while working / when working

In this sentence, it sets the background action:

• Ben ofiste çalışırken... = while I am working in the office...

Because the first clause is not the main statement. It is a subordinate clause meaning while I work / while I’m working.

In Turkish, when one action is the background for another, the background action is often put into a -ken clause:

• Ben ofiste çalışırken arkadaşım markette alışveriş yapıyor. = While I’m working in the office, my friend is shopping at the market.

If you said:

• Ben ofiste çalışıyorum, arkadaşım markette alışveriş yapıyor.

that would mean more like:

• I am working in the office, and my friend is shopping at the market.

That version simply joins two main clauses. The -ken version specifically gives the sense of while.

Not very strongly on its own. -ken mainly shows a time relationship: while / when.

The exact time is usually understood from the main verb and the context.

So çalışırken can mean things like:

• while working
• while I was working
• when I work

In your sentence, because the main verb is yapıyor (is doing / is shopping), the whole sentence is naturally understood as a present-time scene.

Because Turkish is using the locative case, which means in / at.

The locative ending has four forms:

• -de
• -da
• -te
• -ta

The choice depends on:

1. vowel harmony
2. whether the final consonant is voiced or voiceless

ofiste

• base word: ofis
• final sound: s (voiceless)
• so d changes to t
• result: ofiste = in the office

markette

• base word: market
• final sound: t (voiceless)
• so the ending is -te
• result: markette = in/at the market

So these are not random spellings; they follow regular sound rules.

Because arkadaşım means my friend.

The ending -ım / -im / -um / -üm is a possessive suffix meaning my.

So:

• arkadaş = friend
• arkadaşım = my friend

Turkish often uses possessive endings instead of a separate word like my.

Because alışveriş yapmak is the normal Turkish expression for to shop / to do shopping.

Here:

• alışveriş = shopping
• yapmak = to do / to make
• alışveriş yapmak = to shop

This is very common in Turkish. Many actions are expressed as:

• a noun
• plus yapmak or sometimes etmek

So alışveriş yapıyor literally looks like is doing shopping, but it naturally means is shopping.

Because -yor is the common Turkish ending for an ongoing action.

So:

• yapmak = to do
• yapıyor = is doing

In this sentence, alışveriş yapıyor means is shopping or is doing shopping right now / in the scene being described.

It is the main verb of the sentence, so it carries the main tense information.

Not completely. Turkish word order is flexible, although some orders sound more natural than others.

The given sentence is natural because it presents:

1. the background clause first
2. the main action second

• Ben ofiste çalışırken arkadaşım markette alışveriş yapıyor.

You could also rearrange parts for emphasis, for example:

• Arkadaşım markette alışveriş yapıyor, ben ofiste çalışırken.

But that sounds more marked or stylistically different. The original order is the most neutral for everyday use.

Usually it suggests that the actions are happening at the same time, but not necessarily at the exact same second in a super precise way.

It describes overlapping actions:

• I am working in the office
• my friend is shopping at the market

So the meaning is basically while one thing is going on, the other is also going on.

In real use, it can describe:

• a specific moment right now
• a situation around a certain time
• a scene someone is narrating

Yes.

You could say:

• Arkadaşım markette alışveriş yaparken ben ofiste çalışıyorum.

That means essentially the same thing:

• While my friend is shopping at the market, I am working in the office.

The main difference is which action you choose to present as the background and which one you make the main statement. Turkish allows either structure.

Because Turkish often expresses meanings like while, when, as, or during the time that through suffixes rather than separate words.

In English, you usually need a separate word:

• while I work
• when I work

In Turkish, that meaning is built into the verb form:

• çalışırken

This is a very common feature of Turkish grammar: a lot of information is packed into endings instead of separate helper words.