Pielęgniarka mierzy temperaturę przed szczepieniem.

Because it is the direct object of the verb mierzy (measures / is measuring), so it takes the accusative case.

• nominative: temperatura
• accusative: temperaturę

In this sentence:

• Pielęgniarka = the nurse
• mierzy = measures / is measuring
• temperaturę = the temperature

So Polish changes the noun ending to show its role in the sentence.

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

So:

• basic form: szczepienie = vaccination
• after przed: przed szczepieniem = before the vaccination

This is a very useful pattern to remember:

• przed obiadem = before lunch
• przed wizytą = before the visit
• przed szczepieniem = before the vaccination

Mierzy is the 3rd person singular present tense form of mierzyć.

That means it can translate as:

• measures
• is measuring

depending on context.

Here are a few forms:

• ja mierzę = I measure / am measuring
• ty mierzysz = you measure / are measuring
• on/ona mierzy = he/she measures / is measuring

So Pielęgniarka mierzy... means The nurse measures / is measuring...

Mierzyć is imperfective.

In Polish, the imperfective verb is used for:

• ongoing actions
• repeated actions
• general facts
• present tense

Since this sentence describes what is happening now or what nurses generally do before a vaccination, mierzy is the natural choice.

A related perfective verb is often zmierzyć:

• Pielęgniarka mierzy temperaturę. = The nurse is measuring the temperature.
• Pielęgniarka zmierzy temperaturę. = The nurse will measure the temperature / will finish measuring it.

Because Polish does not have articles like a/an and the.

So:

• pielęgniarka can mean a nurse or the nurse
• temperaturę can mean a temperature or the temperature
• szczepieniem can mean a vaccination or the vaccination

The exact meaning comes from context, not from an article.

Yes. Pielęgniarka is the standard word for a female nurse.

The male form is:

• pielęgniarz = male nurse

In many contexts, Polish uses the grammatically gendered profession word that matches the person being described. Since the sentence says pielęgniarka, we understand the nurse is female.

No, Polish word order is more flexible than English because cases show the grammatical roles.

The neutral, most natural order here is:

• Pielęgniarka mierzy temperaturę przed szczepieniem.

But other orders are possible for emphasis, for example:

• Przed szczepieniem pielęgniarka mierzy temperaturę.
  This emphasizes before the vaccination.

Even though the order changes, the cases still show who is doing what.

Here szczepienie means vaccination or shot.

It comes from the verb szczepić = to vaccinate.

So:

• szczepienie = vaccination
• przed szczepieniem = before the vaccination / before getting vaccinated

In everyday medical context, this is a very common word.

A learner-friendly pronunciation is roughly:

• temperaturę ≈ tem-pe-ra-TOO-reh with a nasal quality at the end

The letter ę is a nasal vowel. At the end of a word, many speakers pronounce it less strongly nasally than learners expect, often somewhat like e with slight nasalization.

So you do not need to overdo it. A natural-sounding approximation is better than an exaggerated nasal sound.

A rough English-style guide is:

• pielęgniarka ≈ pye-leng-NYAR-ka

A few helpful notes:

• pie here sounds more like pye
• ń / ni before a vowel can sound like ny
• gniar has that nyar-like quality

You do not need a perfect accent immediately; the main thing is to keep the stress in the right place.

In Polish, stress is usually on the second-to-last syllable.

So:

• pielęgniarka → pie-lęg-NIAR-ka
• mierzy → MIE-rzy
• temperaturę → tem-pe-ra-TU-rę
• szczepieniem → szcze-PIE-niem

That regular stress pattern is one of the helpful things about Polish pronunciation.

Yes. In medical context, mierzyć temperaturę is the normal way to say to take someone’s temperature.

Polish often uses the literal verb measure where English commonly says take.

So this sentence naturally means that the nurse is checking the patient’s temperature before vaccination.

Yes, that is possible, but it is slightly different.

• mierzy temperaturę = measures / takes the temperature
• sprawdza temperaturę = checks the temperature

In a medical setting, mierzy temperaturę is more precise if the nurse is actually using a thermometer. Sprawdza temperaturę is a bit broader and can sound like she is checking it in general.

So the original sentence is the most exact and natural if we mean a real temperature measurement.