Akşamüstü sahilde kestane yemek için arkadaşlarımla randevulaştım.

Akşamüstü is the part of the day around late afternoon / early evening, when the evening is approaching but it is not fully evening yet.

So it is not exactly the same as:

• öğleden sonra = afternoon
• akşam = evening

It has the sense of toward evening or in the late afternoon.

Because -de / -da is the locative suffix, which means in / at / on a place.

• sahil = beach, shore
• sahilde = at the beach / on the beach / by the seaside

In this sentence, it tells you where the planned meeting/eating is connected to.

Here, yemek means to eat.

That is because Turkish dictionary verb forms usually end in -mek / -mak:

• gitmek = to go
• gelmek = to come
• yemek = to eat

It is true that yemek can also be a noun meaning food / meal, but in this sentence it is clearly the verb infinitive because it is followed by için and forms a purpose expression:

• kestane yemek için = in order to eat chestnuts

İçin often means for, but after a verb in the infinitive it commonly means:

• for the purpose of
• in order to

So:

• kestane yemek için = to eat chestnuts / in order to eat chestnuts

This whole part explains why the speaker arranged the meeting.

Arkadaşlarımla means with my friends.

It breaks down like this:

• arkadaş = friend
• arkadaşlar = friends
• arkadaşlarım = my friends
• arkadaşlarımla = with my friends

The ending -la / -le means with.

So this word contains:

• the noun
• plural
• possessive (my)
• comitative/instrumental (with)

That kind of stacking is very normal in Turkish.

Randevulaştım means something like:

• I arranged to meet
• I made plans to meet
• I set up a meeting

It comes from randevu (appointment, date, arranged meeting) plus verbal endings.

In this sentence, it does not mean that the meeting already happened. It means the speaker made the arrangement.

So the focus is on the planning, not on the actual meetup.

A useful rough breakdown is:

• randevu = appointment / arranged meeting
• -laş- = become / do mutually / get into a state together
• -tı- / -dı- = past tense
• -m = I

So randevulaştım is approximately I arranged with someone / I made an appointment to meet.

You do not need to memorize every part perfectly at first, but it helps to know that Turkish often builds verbs this way from nouns.

Because Turkish normally prefers verb-final word order.

A very common pattern is:

time + place + purpose/reason + people + verb

So here:

• Akşamüstü = time
• sahilde = place
• kestane yemek için = purpose
• arkadaşlarımla = with my friends
• randevulaştım = I arranged to meet

English usually puts these pieces in a different order, but in Turkish the main verb often comes last.

Because kestane here is being used in a more general, non-specific way.

• kestane yemek = to eat chestnuts
• kestaneyi yemek = to eat the chestnut / the specific chestnuts

Turkish often uses the bare noun when talking about an activity in general. Compare:

• kahve içmek = to drink coffee
• kitap okumak = to read books / read a book in a general sense
• kestane yemek = to eat chestnuts

If you meant specific chestnuts already known in context, then the accusative form could be used.

Not exactly.

• randevulaşmak = to arrange to meet, to make an appointment
• buluşmak = to meet up

So:

• Arkadaşlarımla randevulaştım. = I arranged to meet my friends.
• Arkadaşlarımla buluştum. = I met up with my friends.

That is an important difference. The sentence you gave is about the arrangement, not the actual meeting itself.

Yes. Turkish word order is flexible, and changing it often changes emphasis, not the basic meaning.

For example, you could also say:

• Arkadaşlarımla akşamüstü sahilde kestane yemek için randevulaştım.
• Sahilde akşamüstü kestane yemek için arkadaşlarımla randevulaştım.

These are all understandable. The original sentence sounds natural and simply presents the information in a neutral way.

Yes, it is natural and understandable.

It means that the speaker made plans with their friends to meet at the beach in the late afternoon in order to eat chestnuts.

A native speaker might also choose slightly different verbs depending on nuance, but your sentence is perfectly normal. The main thing to notice is that randevulaştım emphasizes the arranging/planning part.