Przed egzaminem stres rośnie, więc trudno mi spać.

Because the preposition przed normally requires the instrumental case when it means before in time or in front of in space.

• basic noun: egzamin
• instrumental singular: egzaminem

So:

• przed egzaminem = before the exam

This is a pattern worth remembering:

• przed lekcją = before the lesson
• przed spotkaniem = before the meeting
• przed obiadem = before dinner

So egzaminem is there because of the grammar of przed.

Because stres is the subject of the verb rośnie, and in this sentence the subject is in the nominative case, which is the basic dictionary form.

So:

• stres = stress
• stres rośnie = stress is increasing / stress increases

Only egzamin changes form here, because it comes after the preposition przed. The noun stres does not need to change, since it is the thing doing the action of rośnie.

Rośnie is the 3rd person singular present form of rosnąć, which literally means to grow.

In this sentence, it is used in a natural figurative way:

• stres rośnie = stress grows
• more naturally in English: stress increases or stress builds up

Polish often uses verbs like rosnąć for abstract things too, not only physical things:

• temperatura rośnie = the temperature is rising
• napięcie rośnie = tension is rising
• stres rośnie = stress is rising

Because więc means so, therefore, or thus, and it introduces a new clause. In standard Polish spelling, a comma is normally used before conjunctions like this when they connect clauses.

So the sentence is divided like this:

• Przed egzaminem stres rośnie
• więc trudno mi spać

That comma helps show the logical connection:

• stress rises
• so it is hard for me to sleep

No, they are related in meaning, but they do different jobs.

• więc = so / therefore
  It introduces a result.
• bo = because
  It introduces a reason.

In this sentence:

• Przed egzaminem stres rośnie, więc trudno mi spać.
• Stress rises before the exam, so it is hard for me to sleep.

If you used bo, the logic would go in the other direction:

• Trudno mi spać, bo przed egzaminem stres rośnie.
• It is hard for me to sleep because stress rises before the exam.

So they are not interchangeable, even though both connect ideas.

Because Polish often uses an impersonal structure here.

• trudno = hard / difficult
• mi = to me / for me
• spać = to sleep

So literally, the structure is closer to:

• hard for me to sleep

This is a very common Polish pattern:

• trudno mi mówić = it is hard for me to speak
• łatwo jej zrozumieć = it is easy for her to understand
• przyjemnie nam tu siedzieć = it is pleasant for us to sit here

English usually needs a dummy subject it:

• It is hard for me to sleep

Polish does not need that kind of subject here.

Both forms can mean me, but mi is the usual unstressed dative form and is the normal choice in this kind of sentence.

So:

• trudno mi spać = it is hard for me to sleep

The form mnie is usually used when:

1. you want emphasis
2. it comes after a preposition
3. the rhythm of the sentence requires it

Compare:

• Trudno mi spać. = neutral
• Mnie trudno spać. = I find it hard to sleep / harder emphasis on me

So in your sentence, mi is the natural everyday form.

Because after expressions like trudno mi, Polish often uses an infinitive to say what action is difficult.

Structure:

• trudno + person + infinitive

Examples:

• Trudno mi spać. = It is hard for me to sleep.
• Trudno mu pracować. = It is hard for him to work.
• Trudno nam to zrozumieć. = It is hard for us to understand this.

So spać stays in the infinitive because it names the action itself: to sleep.

Yes, Polish word order is fairly flexible, but different orders sound slightly different in focus or style.

For example:

• Przed egzaminem stres rośnie = neutral, natural
• Przed egzaminem rośnie stres = also possible, slightly more literary or focused on the process of rising
• więc trudno mi spać = neutral
• więc mi trudno spać = possible, but less neutral and more marked

Polish often keeps the most neutral order when teaching beginners:

• time expression first: Przed egzaminem
• subject: stres
• verb: rośnie

Then:

• connector: więc
• impersonal phrase: trudno mi spać

So other word orders may be possible, but the original version is a very good standard model.

Usually before the exam in this context, but Polish does not have articles, so the exact English choice depends on context.

Polish:

• egzamin can mean exam, an exam, or the exam

Here, because it sounds like a specific known event, English often uses:

• before the exam

But in a more general statement, English could also say:

• before an exam, stress increases

So the Polish form itself does not tell you article choice directly.

Not exactly. It means it is hard for me to sleep or I find it difficult to sleep. That suggests difficulty, but not absolute impossibility.

Compare:

• trudno mi spać = it is hard for me to sleep
• nie mogę spać = I can't sleep

In many real-life situations, the meanings may overlap, but grammatically they are different:

• trudno mi spać focuses on difficulty
• nie mogę spać focuses on inability

So your sentence sounds a bit softer and more descriptive than simply I can't sleep.

A rough pronunciation guide for an English speaker is:

• Przed egzaminem ≈ pshet egzah-MEE-nem
• stres rośnie ≈ stres ROSH-nye
• więc trudno mi spać ≈ vyents TROOD-no mee spach

A few useful sound notes:

• rz in przed sounds like the zh sound in measure, but after p it is often devoiced and sounds closer to sh
• ś is a soft sh-like sound
• ń is like the ny sound in canyon
• ą and ę are nasal vowels, though in real speech they often change depending on the following sound
• ć at the end of spać is a soft ch-like sound

You do not need perfect phonetics at first; the most important thing is to stress the correct syllables:

• egzaMInem
• ROŚnie
• TRUDno
• spać is one syllable