Мій двоюрідний брат приїде на весілля.

Мій means my.

It is мій because it has to agree with брат, which is:

• masculine
• singular
• in the nominative case here

So:

• мій брат = my brother
• моя сестра = my sister
• моє весілля = my wedding

Ukrainian possessives change form depending on the noun they describe.

Yes. Двоюрідний брат means male cousin.

Literally, the words look like:

• двоюрідний = cousin-related
• брат = brother

But together, двоюрідний брат is the normal way to say cousin (male).

For a female cousin, you would say:

• двоюрідна сестра

So Ukrainian often makes this distinction:

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

Because standard Ukrainian usually specifies the cousin’s gender.

English uses one word, cousin, for both men and women. Ukrainian commonly uses:

• двоюрідний брат
• двоюрідна сестра

So when translating from English, Ukrainian often forces you to be more specific than English does.

Not literally. In this expression, брат is part of the fixed phrase двоюрідний брат, which means cousin.

So you should understand:

• брат alone = brother
• двоюрідний брат = male cousin

It is not saying the person is both a brother and a cousin. It is simply the standard Ukrainian expression.

Приїде is future tense.

It means will arrive or will come.

The verb is from приїхати, which is a perfective verb. Perfective verbs often give a simple future form like this:

• я приїду = I will arrive
• він/вона приїде = he/she will arrive
• вони приїдуть = they will arrive

So in your sentence:

• Мій двоюрідний брат приїде на весілля.
• My cousin will come to the wedding.

Because приїде expresses a single completed arrival in the future.

That is exactly what perfective verbs are good at: one whole event, seen as completed.

Compare:

• приїде = will arrive / will come once, as a completed event
• буде приїжджати = will be coming / will come repeatedly or in a more ongoing sense

In this sentence, the idea is simple: the cousin will show up at the wedding. So приїде is the natural choice.

Yes, usually it suggests arriving by some means of transport rather than on foot.

Very roughly:

• прийти = come on foot / come
• приїхати = come by vehicle / arrive

In real usage, приїхати is very common when talking about coming from another place, especially for an event. Even if English just says come, Ukrainian may prefer приїхати if travel is involved.

So приїде на весілля sounds very natural for someone traveling to attend a wedding.

Because Ukrainian often uses на with the accusative case for going to events.

So:

• на весілля = to the wedding
• на концерт = to the concert
• на вечірку = to the party
• на роботу = to work

This is a very common pattern:

• movement toward an event/place of activity → на + accusative

It is in the accusative case, because it follows на in a phrase of motion: на весілля.

However, весілля is a neuter noun, and for many neuter nouns the nominative and accusative forms are the same. So it looks unchanged:

• nominative: весілля
• accusative: весілля

That is why you do not see a different ending here.

Because до весілля usually means before the wedding or up to the wedding, not to the wedding event.

Compare:

• приїде на весілля = he will come to the wedding
• приїде до весілля = he will arrive before the wedding

So на весілля is the correct choice for attending the event.

No. Ukrainian word order is fairly flexible, and changing it often changes emphasis, not the core meaning.

Neutral order:

• Мій двоюрідний брат приїде на весілля.

Other possible orders:

• На весілля приїде мій двоюрідний брат.
  This can emphasize to the wedding
• Приїде на весілля мій двоюрідний брат.
  This can sound more literary or emphasize who will come

The version you have is a very normal, neutral sentence.

No. Ukrainian has no articles like English a and the.

So весілля can mean:

• a wedding
• the wedding

The exact meaning depends on context. In your sentence, if the wedding is already known from context, English naturally translates it as the wedding.

The letter ї is pronounced roughly like yi.

So приїде is pronounced approximately like:

• pry-YI-de

The important point is that ї is not the same as і:

• і = roughly ee
• ї = roughly yi

This letter is very characteristic of Ukrainian.

Sometimes you may hear кузен, but двоюрідний брат is the standard native Ukrainian expression.

So for a learner, the safest and most useful choice is:

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

Кузен exists, but it can sound more borrowed, less neutral, or less common depending on the speaker and context.

You would need to change both the possessive and the noun phrase:

• Моя двоюрідна сестра приїде на весілля.

Changes:

• мій → моя because сестра is feminine
• двоюрідний брат → двоюрідна сестра

The rest of the sentence stays the same:

• приїде на весілля = will come to the wedding