У нас короткий дедлайн по эссе: я думала, что дедлайн в пятницу, но оказалось, что эссе нужно сдавать уже в четверг.

Yes, literally у нас means by us / at our place / with us, but in Russian it is very often used to express we have.

So:

• У нас короткий дедлайн по эссе = We have a short deadline for the essay

This is a very common Russian pattern:

• У меня есть книга = I have a book
• У нас экзамен завтра = We have an exam tomorrow

In this sentence, у нас means something like for us / in our situation.

Yes. Короткий literally means short, and with time-related words it often means not much time.

So короткий дедлайн means:

• a short deadline
• a tight deadline

Even though дедлайн is an English loanword, Russian still treats it like a normal masculine noun, so the adjective agrees with it:

• короткий дедлайн
• жёсткий дедлайн
• новый дедлайн

A more native-sounding Russian alternative could be короткий срок or сжатые сроки, but дедлайн is very common in modern informal speech.

По эссе means for the essay or regarding the essay.

The preposition по often has a broad meaning in Russian, including:

• about
• for
• on the topic of
• connected with

So:

• дедлайн по эссе = the deadline for the essay
• вопрос по грамматике = a question about grammar
• задание по истории = an assignment for history

You could not normally just say короткий дедлайн эссе in standard Russian. The по helps show the relationship clearly.

Because the past tense in Russian agrees with the speaker’s gender.

• я думал = I thought (male speaker)
• я думала = I thought (female speaker)

So this sentence tells us that the speaker is female.

This is completely normal in Russian past tense:

• я устал / я устала = I got tired
• я забыл / я забыла = I forgot

With days of the week, Russian often uses в + accusative to mean on:

• в понедельник = on Monday
• в пятницу = on Friday
• в четверг = on Thursday

So дедлайн в пятницу means the deadline is on Friday.

You may also see на пятницу in some contexts, especially when something is scheduled for Friday:

• экзамен перенесли на пятницу = the exam was moved to Friday

But here в пятницу is the natural way to say that the deadline falls on that day.

Оказалось means it turned out.

It comes from the verb оказаться. In this sentence it is used impersonally, so there is no clear subject like it in English, but English usually translates it with it turned out.

• оказалось, что... = it turned out that...

So:

• но оказалось, что... = but it turned out that...

This is a very common Russian structure.

Examples:

• Оказалось, что он прав. = It turned out that he was right.
• Оказалось, что магазин закрыт. = It turned out that the store was closed.

Нужно means it is necessary / one needs to / must, and it is very commonly followed by an infinitive.

So:

• эссе нужно сдавать = the essay needs to be handed in
• more literally: it is necessary to hand in the essay

This construction is impersonal. Russian often avoids directly saying we must or you must when the meaning is obvious from context.

Compare:

• Мне нужно идти. = I need to go.
• Нужно работать. = It’s necessary to work / We need to work.

Here the sentence is talking about a requirement, not about who specifically is doing it.

That is a very good question. Many learners would expect сдать, and in fact эссе нужно сдать уже в четверг would also sound very natural.

The difference is roughly this:

• сдать = perfective, focuses on the completed result: to submit / to hand in
• сдавать = imperfective, focuses more on the action/process or the general requirement

In everyday speech, especially when talking about deadlines, both can appear. In this sentence, нужно сдавать sounds like the essay is supposed to be handed in already on Thursday.

If you said нужно сдать уже в четверг, that would put slightly more focus on completing the submission by Thursday.

So the sentence is natural, but yes, сдать is also very plausible here.

Уже usually means already, but in time expressions it often means as early as or so soon as.

So:

• уже в четверг = already on Thursday
• more naturally in English here: as early as Thursday

It shows the speaker’s surprise: Thursday is earlier than expected.

Compare:

• Он уже дома. = He is already home.
• Экзамен уже завтра. = The exam is already tomorrow.
• Нужно прийти уже в семь. = You have to come as early as seven.

Эссе is an indeclinable noun in Russian, which means its form usually does not change across cases.

So you get:

• эссе as subject
• эссе as object
• по эссе
• с эссе

The case is shown by the surrounding words, not by changing the noun itself.

This is common with many borrowed words in Russian, especially ones ending in -е, -и, -о, or -у.

The colon introduces an explanation of the first statement.

The structure is:

• У нас короткий дедлайн по эссе:
  explanation follows

Then the explanation is:

• я думала, что дедлайн в пятницу, но оказалось, что эссе нужно сдавать уже в четверг

So the colon works a bit like namely / here’s what I mean.

The commas are there because of the что clauses:

• я думала, что...
• оказалось, что...

And there is a comma before но because it joins two clauses:

• ..., но оказалось, что...

Дедлайн is a very common modern borrowing, especially in:

• student speech
• office/work contexts
• informal conversation
• online communication

So the sentence sounds natural in modern Russian.

However, in more formal or traditional Russian, you might see:

• срок
• крайний срок
• срок сдачи

For example:

• Крайний срок сдачи эссе — четверг. = The deadline for the essay is Thursday.

So дедлайн is common and natural, but it is more conversational and modern than срок.

Yes, absolutely.

• Но эссе нужно сдавать уже в четверг = But the essay needs to be handed in already on Thursday

That is simpler and more direct.

By adding оказалось, the speaker emphasizes the discovery or surprise:

• I thought X, but it turned out Y

So оказалось adds the idea of finding out that your earlier assumption was wrong. That makes the sentence sound more natural and expressive.