Üretim tahmini geri ödeme süresini değiştiriyor.

It breaks down like this:

Üretim tahmini = production estimate
geri ödeme süresini = the payback period
değiştiriyor = is changing / changes

So the basic structure is:

subject + object + verb

That is the normal neutral word order in Turkish.

Here, -i is not the accusative.

In üretim tahmini, the word tahmini is really:

tahmin + i

That -i is the suffix commonly used in a Turkish noun compound. So:

üretim tahmini = production estimate
literally something like production its-estimate

This is a very common Turkish pattern.

A useful comparison:

üretim tahmini = production estimate
tahmini üretim = estimated / approximate production

So word order matters a lot here.

Because it contains more than one ending.

Break it down like this:

süre = period / duration
süre-si = its period / period of
süre-si-ni = the period (as a specific direct object)

So in the full phrase:

geri ödeme süresi = payback period
geri ödeme süresini = the payback period (object of the verb)

The extra n is a buffer consonant that appears before the accusative ending after a possessive suffix.

So:

• -si = compound/possessive ending
• -ni = accusative with buffer n

Because of the accusative ending.

In Turkish, a specific direct object often takes the accusative ending. Here that is the -ni at the end of süresini.

So:

geri ödeme süresini = the thing being changed

That means üretim tahmini is the subject, and geri ödeme süresini is the object.

Because Turkish normally uses SOV word order:

Subject + Object + Verb

So:

Üretim tahmini
geri ödeme süresini
değiştiriyor

English usually prefers SVO order, so this can feel backwards at first.

Turkish can move parts around for emphasis, but the most neutral version usually puts the verb last.

Because değiştirmek means to change something, while değişmek means to change or to undergo change.

Compare:

Fiyat değişiyor. = The price is changing.
The price itself changes.

Bu karar fiyatı değiştiriyor. = This decision changes the price.
Something causes the price to change.

In your sentence, there is a direct object:

geri ödeme süresini

So the verb needs to be the transitive one:

değiştiriyor = is changing / changes

Not always.

The ending -iyor is often called the present continuous, but in real Turkish it can also be used for:

• something happening right now
• a current trend
• a general present meaning, especially in explanations or technical contexts

So değiştiriyor can mean either:

is changing
or
changes

The best translation depends on the context.

Literally:

geri = back
ödeme = payment

Together, geri ödeme means repayment or payback.

So:

geri ödeme süresi = repayment period / payback period

This is another example of how Turkish often builds longer meanings by combining nouns instead of using prepositions.

Turkish does not have articles like English a and the.

Instead, Turkish often shows definiteness through:

• context
• word order
• case endings

Here, geri ödeme süresini is marked as a specific object by the accusative ending, so it often corresponds to the payback period in English.

For the subject, üretim tahmini could be understood as the production estimate or a production estimate, depending on context.

If Turkish wants to clearly say a, it can use bir:

bir üretim tahmini = a production estimate

You should read it as one noun phrase:

üretim tahmini = production estimate

This is important, because if you read the words separately, you may misunderstand the sentence.

A good rule is:

when two nouns appear together in this pattern, they often form a compound meaning a single idea.

That is exactly what is happening here with both:

üretim tahmini
and
geri ödeme süresi