Моя двоюрідна сестра приїде на весілля.

It is the normal Ukrainian way to say female cousin.

More literally, Ukrainian often uses family terms with брат or сестра:

• двоюрідна сестра = female cousin
• двоюрідний брат = male cousin

So instead of one common everyday word that works like English cousin, Ukrainian very often specifies gender.

Because сестра is a feminine singular noun.

In Ukrainian, words that describe or belong to a noun usually agree with it in gender, number, and case.

Here:

• сестра = feminine singular
• моя = feminine singular form of my
• двоюрідна = feminine singular form of cousin-related

So the phrase must be:

• моя двоюрідна сестра

If the noun were masculine, you would use masculine forms:

• мій двоюрідний брат

You would say:

Мій двоюрідний брат приїде на весілля.

The changes are:

• моя → мій
• двоюрідна сестра → двоюрідний брат

That is because брат is masculine.

Because this verb is perfective.

In Ukrainian, perfective verbs often form the future with a simple one-word form:

• приїхати = to arrive / to come by transport, as a completed event
• приїде = will arrive

This is very common:

• напише = will write
• зробить = will do
• прийде = will come

If you used an imperfective verb, the future would often be formed differently, for example with буде:

• буде приїжджати = will be coming / will come repeatedly

But in your sentence, the idea is one completed future arrival, so приїде is exactly right.

These are related but different verbs.

• прийде comes from прийти = to come, often literally to come on foot
• приїде comes from приїхати = to come / arrive by transport or from another place

So приїде suggests that the cousin will travel in to the wedding, for example by car, train, or bus. That sounds very natural if someone is coming from another town or city.

If you said прийде на весілля, it would sound more like she’ll come/go to the wedding without the travel-by-vehicle nuance, or even literally walk there depending on context.

Because Ukrainian commonly uses на with many events.

So you say:

• на весілля = to the wedding
• на концерт = to the concert
• на вечірку = to the party
• на зустріч = to the meeting

This is just the normal preposition pattern for attending or going to an event.

It is in the accusative case after на, but for this noun the accusative looks the same as the nominative.

So:

• nominative: весілля
• accusative: весілля

This is normal for many neuter inanimate nouns in Ukrainian: the nominative and accusative are often identical.

Here is the breakdown:

• моя двоюрідна сестра — nominative

  • This is the subject of the sentence, the person doing the action.

• приїде — verb

• на весілля — accusative after the preposition на

  • This expresses destination/purpose: to the wedding

So the structure is basically:

[subject in nominative] + [future verb] + [prepositional phrase with accusative]

Yes. Ukrainian word order is quite flexible.

The most neutral order here is:

Моя двоюрідна сестра приїде на весілля.

But you could also say:

• На весілля приїде моя двоюрідна сестра.
• Приїде моя двоюрідна сестра на весілля.

The basic meaning stays the same, but the emphasis changes.

For example:

• На весілля приїде моя двоюрідна сестра puts more focus on the wedding
• Моя двоюрідна сестра приїде на весілля is the most straightforward, neutral version

Yes, if the context already makes it clear whose cousin you mean.

You could say:

Двоюрідна сестра приїде на весілля.

But then, depending on context, it may sound like:

• my cousin
• the cousin
• a cousin

Ukrainian has no articles like English a and the, so context does a lot of work. Keeping моя makes the meaning explicit: my female cousin.

Because Ukrainian does not have articles.

English needs words like:

• a
• the

Ukrainian usually does not use anything equivalent. Definiteness is understood from:

• context
• word order
• possessives like моя
• the situation itself

So моя двоюрідна сестра already naturally means my cousin, and no article is needed.