Мой день рождения девятого апреля, поэтому в апреле я обычно беру выходной.

День рождения is the standard Russian way to say birthday.

Literally, it is:

• день = day
• рождения = of birth

So the whole phrase means day of birth.

In Russian, this is a fixed expression, and рождения is in the genitive case because it depends on день: the day of what? → of birth.

Then мой agrees with день, which is masculine singular:

• мой день рождения = my birthday

When Russians give a date like the ninth of April, they normally use:

• an ordinal number in the genitive
• the month also in the genitive

So:

• девятое апреля would not be correct here
• девятый апреля is also incorrect

The correct form is:

• девятого апреля = on the ninth of April / April 9th

Why? Because the full underlying idea is something like:

• девятого числа апреля = of the ninth date/day of April

The word числа is usually omitted, but the genitive pattern remains.

A few examples:

• первого мая = May 1st
• десятого июня = June 10th
• двадцать пятого декабря = December 25th

Russian often omits is / are in the present tense.

So:

• Мой день рождения девятого апреля literally looks like My birthday ninth of April
• but it means My birthday is on April 9th

This is completely normal in Russian.

Compare:

• Он врач = He is a doctor
• Москва — столица России = Moscow is the capital of Russia
• Мой день рождения девятого апреля = My birthday is on April 9th

If you translated word-for-word into English, it would sound incomplete, but in Russian it is standard.

Because the two parts express time in different ways.

1. девятого апреля

This gives a specific date: April 9th.
Russian uses the genitive for this date format.

2. в апреле

This means in April, referring to the month in general.
After в meaning in, Russian uses the prepositional case for months:

• в январе = in January
• в феврале = in February
• в апреле = in April

So:

• девятого апреля = on April 9th
• в апреле = in April

Same month, different grammar.

Поэтому means therefore, so, or that’s why.

In this sentence:

• Мой день рождения девятого апреля, поэтому в апреле я обычно беру выходной.
• My birthday is on April 9th, so I usually take a day off in April.

The comma is used because поэтому connects two clauses:

1. Мой день рождения девятого апреля
2. в апреле я обычно беру выходной

This is very common in Russian.

You can think of поэтому as introducing a result:

• fact → result

Examples:

• Я устал, поэтому рано лёг спать. = I was tired, so I went to bed early.
• Сегодня холодно, поэтому мы дома. = It’s cold today, so we’re staying home.

Yes — and that is exactly how Russian expresses this idea.

• брать / взять = to take
• выходной = a day off

So:

• брать выходной = to take a day off

This is very natural Russian.

Examples:

• Я беру выходной в пятницу. = I’m taking Friday off / I’m taking a day off on Friday.
• Он взял выходной вчера. = He took a day off yesterday.

Notice the aspect pair:

• брать = imperfective, often for repeated/habitual action
• взять = perfective, often for one completed action

Since the sentence says обычно (usually), the imperfective беру is the right choice.

Because here выходной is the direct object of беру, so it is in the accusative case.

But since выходной is an inanimate masculine noun/adjective-like noun, its accusative form is the same as the nominative:

• nominative: выходной
• accusative: выходной

So:

• я беру выходной = I take a day off

This word originally comes from the adjective meaning day-off / non-working, but in modern Russian it is also commonly used as a noun:

• У меня сегодня выходной. = I have a day off today.
• Я беру выходной. = I’m taking a day off.

Yes, absolutely. Both are natural, but they feel slightly different.

Мой день рождения девятого апреля

This is straightforward and neutral:

• My birthday is on April 9th

У меня день рождения девятого апреля

This literally means something like:

• I have my birthday on April 9th but in natural English we still translate it as:
• My birthday is on April 9th

Russian often uses у меня for things connected with a person:

• У меня есть брат. = I have a brother
• У меня отпуск в июле. = My vacation is in July
• У меня день рождения завтра. = My birthday is tomorrow

So yes, both versions work.

Yes, Russian word order is flexible, and обычно can move.

In the sentence:

• в апреле я обычно беру выходной

the placement is natural and neutral:

• I usually take a day off in April

You could also hear:

• В апреле я беру выходной обычно — possible, but less natural in neutral speech
• Обычно в апреле я беру выходной — emphasizes usually
• Я обычно беру выходной в апреле — also very natural

Russian word order often changes for:

• emphasis
• topic/focus
• style

So the given version is normal, but not the only possible one.

In Russian, the present tense is often used for habitual/repeated actions, just like in English.

So:

• я обычно беру выходной = I usually take a day off

This does not mean only I am taking one right now.
Because of обычно (usually), it clearly means a repeated habit.

Compare:

• Я пью кофе утром. = I drink coffee in the morning
• Он часто читает вечером. = He often reads in the evening
• Я обычно беру выходной в апреле. = I usually take a day off in April

So the present tense here is exactly what you would expect.

It most often means day off.

In this sentence:

• беру выходной clearly means take a day off

But in other contexts, выходной can refer to a non-working day more generally:

• Сегодня выходной. = Today is a day off
• На выходных = on the weekend

Be careful, though:

• выходной = a day off / non-working day
• выходные = days off, often the weekend

Examples:

• У меня выходной в среду. = I have a day off on Wednesday
• Что ты делаешь на выходных? = What are you doing on the weekend?

So in your sentence, singular выходной is definitely a day off.