Joker hakkı sadece bir kez kullanılıyor.

Joker hakkı means something like the right to use a joker or a joker privilege/chance.

• joker = joker
• hak = right
• hakkı = its/the ... right in a possessed form

In Turkish, this kind of noun phrase is very common:

• öğrenci kartı = student card
• telefon numarası = phone number
• joker hakkı = joker right / right to use a joker

So joker hakkı is a compound noun, not just two separate words placed next to each other.

Because Turkish often forms noun compounds with a special pattern:

• first noun: usually unchanged
• second noun: gets a possessive-style ending

So:

• joker + hak would sound incomplete here
• joker hakkı is the normal compound form

The ending -ı on hakkı is the 3rd person possessive ending, but in compounds it often works more like a standard structure than a literal his/her/its meaning.

Also note the consonant change:

• hak
  • -ı → hakkı

That doubling of k is part of how this word behaves.

Sadece means only.

In this sentence:

• Joker hakkı sadece bir kez kullanılıyor. = The joker right is used only once.

Here sadece is placed before bir kez, so it emphasizes only once.

Turkish word order is somewhat flexible, so you may also see sadece in different positions depending on what is being emphasized. But in this sentence, it naturally modifies bir kez.

Yes. Bir kez means once or literally one time.

• bir = one
• kez = time/occasion

So:

• bir kez = once
• iki kez = twice / two times
• üç kez = three times

It is very similar to bir defa. Both can mean once.
Bir kez often sounds a little more neutral or standard in many contexts, but both are common.

Because kullanılıyor is passive, while kullanıyor is active.

• kullanıyor = is using
• kullanılıyor = is being used

Here the subject is joker hakkı, and it is not doing the action itself. It is the thing being used. So Turkish uses the passive:

• Joker hakkı kullanılıyor. = The joker right is being used.

The passive marker here is -ıl-:

• kullan- = use
• kullan-ıl- = be used
• kullanılıyor = is being used / gets used

This is very common in Turkish. The -yor form usually marks an ongoing or current situation, but in many general statements it can sound natural in English as either:

• is being used
• is used

So this sentence can feel like:

• The joker right is only used once or
• The joker right is being used only once

In practice, the first translation is often the more natural English version if the sentence is stating a rule.

Turkish often uses present forms in ways that cover both a current process and a general rule, depending on context.

Yes, Joker hakkı sadece bir kez kullanılır is also possible, and it may even sound more natural if you are stating a general rule.

Compare:

• kullanılıyor = is being used / is used
• kullanılır = is used / can be used

Very roughly:

• kullanılıyor can sound a bit more like a current system, ongoing procedure, or present practice
• kullanılır often sounds more like a general rule, instruction, or habitual fact

So both are possible, but the nuance can differ slightly.

Turkish usually puts the verb at the end, so kullanılıyor comes last.

The rest of the sentence is arranged like this:

• Joker hakkı = subject/topic
• sadece bir kez = adverbial phrase (only once)
• kullanılıyor = verb

So the structure is roughly:

[subject] + [adverbial expression] + [verb]

This is very typical Turkish word order.

Yes. Joker hakkı is the grammatical subject.

Even though the sentence is passive, the thing affected by the action becomes the subject:

• Birisi joker hakkını kullanıyor. = Someone is using the joker right.

Passive version:

• Joker hakkı kullanılıyor. = The joker right is being used.

So in the passive sentence, joker hakkı is the subject.

Because it is the subject, not the direct object.

Compare:

• Joker hakkı kullanılıyor.
  • joker hakkı = subject
  • no accusative ending

But in an active sentence:

• Oyuncu joker hakkını kullanıyor. = The player is using the joker right.

Here:

• joker hakkını has the accusative ending -nı
• because it is the definite direct object

So:

• hakkı = compound noun form
• hakkını = that same noun in the accusative

Yes, absolutely. It sounds very natural in contexts like:

• game rules
• quiz shows
• competition instructions
• exam regulations

For example, if a system allows only one joker/lifeline, this sentence works well to express that restriction:

• Joker hakkı sadece bir kez kullanılıyor.

In a rulebook or formal instruction, you might also often see:

• Joker hakkı sadece bir kez kullanılabilir. = The joker right can only be used once.
• Joker hakkı sadece bir kez kullanılır. = The joker right is only used once.

So the original sentence is understandable and natural, especially in spoken or practical contexts.