Geri sayım süre sınırını gösteriyor.

Because it is a noun phrase made from two separate words, not a single fused word.

• geri = backward
• sayım = counting

Turkish often builds expressions this way. So geri sayım functions as one idea, but it is still written as two words.

Süre sınırı is a noun compound meaning time limit.

It is built like this:

• süre = duration / allotted time
• sınır = limit / boundary

In Turkish, one noun can modify another very naturally. So süre sınırı literally means something like the limit of the duration/time, which is the normal way to say time limit.

That -ı is part of the Turkish noun-compound pattern.

In many Turkish compounds, the second noun takes a suffix that often looks like a possessive ending:

• süre sınır-ı = time limit

So this is not just süre + sınır. The more complete compound form is süre sınırı.

This is very common in Turkish:

• otobüs durağı = bus stop
• şehir merkezi = city center
• zaman kaybı = loss of time / waste of time

Because the phrase is the direct object of the verb gösteriyor, and it is a specific/definite object.

So:

• süre sınırı = time limit
• süre sınırını = the time limit, as a marked direct object

That final -ı / -i / -u / -ü type ending is the accusative case, which Turkish uses for specific direct objects.

That n is a buffer consonant.

The word is built like this:

• sınır = limit
• sınır-ı = its limit / limit in the compound form
• sınırı-nı = that limit, as a definite direct object

When Turkish adds the accusative after a possessed or compound-marked form, it often inserts n to make pronunciation and structure work smoothly.

So süre sınırını is perfectly regular:

• compound form: süre sınırı
• accusative object form: süre sınırını

Not naturally in this context.

Without the accusative, the object sounds more indefinite or less clearly marked. Turkish usually uses the accusative when the speaker means a specific thing, especially with a verb like show/display.

So:

• süre sınırını gösteriyor = it is showing the time limit
• süre sınırı gösteriyor = less natural here; it can sound incomplete or less idiomatic

In this sentence, süre sınırını is the expected form.

Gösteriyor uses the -iyor form, which is often called the present continuous/progressive.

It is used for:

• something happening right now
• something currently being shown on a screen/device
• sometimes even a present situation in everyday speech

So gösteriyor here is very natural for is showing or shows in the sense of a current display.

By contrast, gösterir is more like:

• a general truth
• a habitual action
• a characteristic behavior

So gösteriyor fits better if the countdown is currently displaying the time limit.

It can mean any of those, depending on context.

The verb göstermek is broader than just physically showing something with your hand. It can also mean:

• show
• display
• indicate

So in a sentence about a countdown, gösteriyor often feels very close to is displaying or is indicating.

The structure helps:

• Geri sayım = subject
• süre sınırını = object
• gösteriyor = verb

A big clue is the accusative ending on süre sınırını. That tells you it is the direct object. So the thing doing the showing must be geri sayım.

Turkish often relies on case endings like this, not just word order.

Yes. It follows the very common Turkish pattern:

Subject + Object + Verb

So:

• Geri sayım = subject
• süre sınırını = object
• gösteriyor = verb

That is one of the most basic and natural sentence orders in Turkish. The verb often comes at the end.

Turkish does not have articles that work like English a/an and the.

Instead, Turkish shows definiteness in other ways, especially through:

• context
• word order
• case marking

Here, the accusative ending in süre sınırını helps show that the object is specific, which is one reason the English meaning often uses the time limit.

It is in the present continuous/progressive form because of -iyor in gösteriyor.

So the sentence describes something that is currently happening or currently true in the situation:

• the countdown is showing
• the countdown is displaying

In everyday Turkish, this form is extremely common, sometimes even where English might simply use the simple present.