Ağabeyim, akşam dolmuş daha boş olacakmış dedi.

Ağabeyim means my older brother.

It breaks down like this:

• ağabey = older brother
• -im = my

So:

• ağabey → older brother
• ağabeyim → my older brother

In Turkish, family words often take possessive endings this way.

In modern Turkish, ğ usually does not sound like a hard English g.

In ağabeyim, it mostly lengthens or smooths the vowel before it, so the word is pronounced roughly like:

• aa-bey-im

A rough English-friendly approximation is:

• AHA-bey-im or AA-bey-im

You may also hear the shorter everyday form abim, which is very common in speech.

The comma shows a pause before the reported content.

So the sentence is structured like:

• My older brother, ... said.

In very neutral writing, many speakers would also write this without a comma:

• Ağabeyim akşam dolmuş daha boş olacakmış dedi.

So the comma is possible, but it is not the most important part of the grammar.

Also, here ağabeyim is best understood as the subject of dedi, not as someone being directly addressed.

Because akşam is functioning as a time adverb here: in the evening / this evening / tonight, depending on context.

Turkish often uses time words with no case ending when they are just telling you when something happens.

Examples of this kind of usage:

• bugün = today
• yarın = tomorrow
• akşam = in the evening / tonight
• sabah = in the morning

So akşam here is perfectly normal as a bare time expression.

Yes, dolmuş is the subject of olacakmış.

That part means something like:

• the dolmuş will apparently be...
• the dolmuş is said to be going to be...

Turkish subjects often appear with no ending at all. That is the normal nominative form.

Also, Turkish does not have English-style articles like a and the, so a bare noun like dolmuş can mean:

• the dolmuş
• a dolmuş
• dolmuşes in a more general sense

The exact reading comes from context.

Daha boş means more empty, which in natural English becomes emptier or often less crowded.

Turkish usually forms comparatives with:

• daha + adjective

So:

• boş = empty
• daha boş = emptier / less full

Other examples:

• büyük = big

• daha büyük = bigger

• ucuz = cheap
• daha ucuz = cheaper

There is no special adjective ending like English -er.

Literally, yes: boş means empty.

But with buses, minibuses, trains, and similar things, Turkish often uses boş in the sense of:

• not crowded
• less full
• with more space
• with more empty seats

So in this sentence, daha boş is probably best understood as less crowded rather than completely empty.

Olacakmış has two parts:

• olacak = will be / is going to be
• -mış = a marker often used for reported information, hearsay, or sometimes inference

So olacakmış means something like:

• apparently it will be
• it is said that it will be
• it will be, I hear

In English, this nuance is often not translated word-for-word, but it is important in Turkish.

Good question. This sentence has two layers of reporting.

• dedi = he said
• -mış inside olacakmış = the content itself is presented as something heard/reported/inferred

So the idea can be:

• My older brother said that apparently the dolmuş would be less crowded in the evening.

This can suggest that your brother was not necessarily making the claim from his own direct knowledge; he may have been passing on something he had heard or understood.

Compare:

• ... daha boş olacak dedi
  = he said it would be less crowded

• ... daha boş olacakmış dedi
  = he said it would apparently be less crowded / that he had heard it would be less crowded

So -mış adds an extra nuance that English often leaves unstated.

Dedi is the third person singular past tense of demek, which means to say.

So:

• demek = to say
• dedi = he/she said

In this sentence, the subject is ağabeyim, so:

• Ağabeyim ... dedi = My older brother said ...

Turkish very often puts the main verb at the end of the sentence, which is why dedi comes last.

It is somewhere between them in feel, but grammatically it works like a reported-speech structure where the content comes before dedi.

Turkish often allows this kind of pattern:

• [what was said] + dedi

A more explicitly textbook-style indirect version would be:

• Ağabeyim, akşam dolmuşun daha boş olacağını söyledi.

That version uses:

• olacağını = that it would be
• söyledi = said

So your original sentence is natural, especially in everyday Turkish, but another common way to express the same idea is with olacağını söyledi.

Yes, Turkish word order is flexible, especially for things like time expressions and focus.

The most important fixed point is that the main verb dedi usually stays at or near the end.

Possible variations include:

• Ağabeyim akşam dolmuş daha boş olacakmış dedi.
• Ağabeyim dolmuşun akşam daha boş olacağını söyledi.

Changing the order can shift emphasis, but not necessarily the basic meaning.

For example, putting akşam earlier helps foreground the time:

• in the evening

Putting dolmuş earlier helps foreground the vehicle.

So learners should think of Turkish word order as flexible but meaningful, not random.