Yarınki toplantıyı erkene aldık, çünkü müdür öğleden sonra müsait değil.

Yarınki means tomorrow’s or the one for tomorrow.

Here, -ki turns yarın (tomorrow) into something that can describe a noun:

• yarın = tomorrow
• yarınki toplantı = tomorrow’s meeting / the meeting tomorrow

This use of -ki is very common with time expressions:

• bugünkü ders = today’s lesson
• dünkü haber = yesterday’s news
• akşamki maç = tonight’s match

So yarınki toplantıyı means the meeting scheduled for tomorrow.

Because toplantı is the specific direct object of the verb, so it takes the accusative ending.

• toplantı = meeting
• toplantıyı = the meeting

The sentence is talking about a particular meeting, not just any meeting. In Turkish, specific direct objects usually take the accusative ending:

• kitap okuduk = we read a book / books
• kitabı okuduk = we read the book

Here:

• Yarınki toplantıyı erkene aldık = We moved the tomorrow meeting earlier

Also notice the buffer consonant -y-:

• toplantı + -(y)ı → toplantıyı

That y appears because the noun ends in a vowel.

Literally, erkene aldık is something like we took it to an earlier time.

• erken = early
• erkene = to earlier / to an earlier time
• aldık = we took

But in natural Turkish, bir şeyi erkene almak means:

• to move something earlier
• to bring something forward

So this is an idiomatic use of almak. Turkish often uses very common verbs like almak in expressions that do not translate word-for-word into English.

Similar scheduling expressions:

• toplantıyı erkene aldık = we moved the meeting earlier
• toplantıyı sonraya aldık = we postponed the meeting / moved it to later

The -e is the dative ending, often meaning to or toward.

In this expression, it marks the idea of movement toward an earlier point in time:

• erken = early
• erkene almak = to move to an earlier time

So the logic is roughly:

• toplantıyı erkene aldık = we moved the meeting to earlier

This is just how the expression works in Turkish. You will also see the matching opposite:

• sonraya almak = to move to later / postpone

So these are worth learning as set phrases:

• erkene almak
• sonraya almak

In Turkish, the verb ending usually shows the subject, so separate subject pronouns are often omitted.

• aldık = we took / we moved

The ending -k here marks we in the past tense form.

So:

• aldım = I took
• aldın = you took
• aldı = he/she/it took
• aldık = we took
• aldınız = you (plural/formal) took
• aldılar = they took

Because Turkish is a pro-drop language, biz (we) is usually unnecessary unless you want emphasis.

Çünkü means because.

In this sentence, it introduces the reason:

• Yarınki toplantıyı erkene aldık, çünkü müdür öğleden sonra müsait değil.
• We moved tomorrow’s meeting earlier, because the manager is not available in the afternoon.

A useful thing to know: after çünkü, Turkish usually keeps normal sentence order. It does not force the verb to the end in some special subordinate-clause way like German does.

So after çünkü, you can often think of it as a regular full sentence:

• müdür öğleden sonra müsait değil = the manager is not available in the afternoon

Öğleden sonra means in the afternoon or literally after noon.

It is made up of:

• öğle = noon
• öğleden = from noon / after noon
• sonra = after

Together, the expression functions as a time phrase:

• öğleden sonra = in the afternoon / after noon

Examples:

• Öğleden sonra geleceğim. = I’ll come in the afternoon.
• Öğleden sonra dersimiz var. = We have class in the afternoon.

In your sentence, it tells us when the manager is not available.

No ending is needed here because müdür is the subject of the second clause.

• müdür = manager / the manager

In:

• müdür öğleden sonra müsait değil

the manager is the person being described, so müdür stays in its basic form.

You would expect müdürü only if it were a specific direct object, for example:

• Müdürü gördüm. = I saw the manager.

But here it is the subject:

• Müdür müsait değil. = The manager is not available.

Müsait değil means is not available, is not free, or is not convenient depending on context.

• müsait = available / free / convenient
• değil = not

So:

• müsait = available
• müsait değil = not available

In Turkish, değil is the standard way to negate nominal and adjectival predicates. Since müsait is an adjective-like predicate, Turkish uses değil rather than a verb like not be.

Examples:

• Müsaitim. = I’m available.
• Müsait değilim. = I’m not available.
• Bu uygun değil. = This is not suitable.

So even though English uses is not, Turkish handles this with the predicate plus değil.

Turkish has no articles like English a/an/the.

Whether something is a meeting or the meeting is understood from context, word order, and case marking.

For example:

• toplantı can mean a meeting or meeting
• toplantıyı strongly suggests the meeting because it is a specific object

Similarly:

• müdür can mean the manager or a manager, depending on context

In this sentence, the meaning is clearly definite:

• yarınki toplantıyı = the specific meeting scheduled for tomorrow
• müdür = the manager already understood in context

Yes. Turkish often allows different but natural alternatives.

For example:

• Yarınki toplantıyı daha erkene aldık.
  = We moved tomorrow’s meeting to an even earlier time.

• Müdür öğleden sonra uygun olmadığı için yarınki toplantıyı erkene aldık.
  = Since the manager is not available in the afternoon, we moved tomorrow’s meeting earlier.

• Yarınki toplantıyı öğleden önceye aldık.
  = We moved tomorrow’s meeting to before noon.

Your original sentence is very natural and conversational. It sounds like something someone would really say in a work setting.