Nasza firma szuka nowego pracownika do biura, ale nie każdy współpracownik lubi zmiany.

Because firma is a feminine singular noun in the nominative case here: it is the subject of the sentence.

The adjective/pronoun nasz must agree with the noun in:

• gender
• number
• case

So:

• nasz = masculine singular
• nasza = feminine singular
• nasze = neuter singular / some plural uses

Since firma is feminine, we get nasza firma = our company.

Because the two nouns have different jobs in the sentence.

• firma is the subject, so it is in the nominative: firma
• pracownika is the object after szukać, and that verb usually takes the genitive, not the accusative

So:

• firma szuka... = the company is looking for...
• szuka pracownika = is looking for an employee

This is one of the important things to remember about Polish: some verbs require cases that do not match what an English speaker would expect.

The verb szukać normally governs the genitive case.

So:

• pracownik = nominative
• pracownika = genitive singular

Examples:

• Szukam klucza. = I’m looking for a key.
• Szukamy nauczyciela. = We’re looking for a teacher.
• Firma szuka pracownika. = The company is looking for an employee.

This is just a case pattern you need to learn with the verb:

• szukać + genitive

Because nowego has to match pracownika in case, gender, and number.

The noun is:

• pracownik = masculine personal singular
• after szukać, it becomes genitive singular: pracownika

The adjective nowy must match that:

• nominative: nowy pracownik
• genitive: nowego pracownika

So:

• nowy pracownik = a new employee
• szuka nowego pracownika = is looking for a new employee

Because do biura means for the office / to the office, while w biurze means in the office.

Here, pracownik do biura means something like:

• an office employee
• an employee for the office
• someone to work in the office

So:

• do biura suggests destination, purpose, or assignment
• w biurze would describe location

Compare:

• Szukamy pracownika do biura. = We’re looking for an office employee.
• Pracownik pracuje w biurze. = The employee works in the office.

Biura is the genitive singular form of biuro.

That is because the preposition do requires the genitive.

So:

• biuro = nominative
• do biura = genitive after do

A very common pattern:

• do domu = to the house / home
• do szkoły = to school
• do biura = to the office

They are related words, but they do not mean the same thing.

• pracownik = employee, worker, staff member
• współpracownik = coworker, colleague

In this sentence:

• firma szuka nowego pracownika = the company wants to hire a new employee
• nie każdy współpracownik lubi zmiany = not every coworker likes changes

So the first word refers to the person being hired, and the second refers to people already working with others in the company.

Also, współpracownik can sometimes mean associate or person someone works with, depending on context, but coworker/colleague is the most natural meaning here.

Because każdy means each / every, and in Polish it is used with a singular noun.

So:

• każdy współpracownik = every coworker
• literally, it is grammatically singular

That is why the phrase stays singular even though the meaning refers to multiple people one by one.

Compare:

• Każdy student musi to zrobić. = Every student must do this.
• Nie każdy współpracownik lubi zmiany. = Not every coworker likes changes.

It means not every coworker.

In other words:

• some coworkers like changes
• some do not

It does not mean no coworker likes changes.

That stronger meaning would be:

• Żaden współpracownik nie lubi zmian. = No coworker likes changes.

So:

• nie każdy = not everyone / not every
• żaden = no one / none / not any

Here zmiany is the accusative plural of zmiana meaning change.

The verb lubić takes the accusative:

• lubić + accusative = to like + object

So:

• zmiana = singular nominative
• zmiany = plural accusative (also nominative plural in form)

That is why:

• lubi zmiany = likes changes

For feminine nouns ending in -a, the plural accusative often looks the same as the plural nominative:

• książki
• zmiany
• kawy

Yes. The noun zmiana can mean:

• change
• shift (as in a work shift)

So zmiany could mean:

• changes
• shifts

But in this sentence, lubi zmiany is naturally understood as likes changes, especially because of the contrast with hiring and workplace attitudes.

If the sentence were about work schedules, zmiany might mean shifts.

Ale means but.

It connects two contrasting ideas:

• Nasza firma szuka nowego pracownika do biura
• ale nie każdy współpracownik lubi zmiany

So the contrast is:

• the company wants something new
• but some coworkers may not welcome that change

It works very much like English but.

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

So:

• firma can mean a company or the company
• pracownika can mean an employee or the employee
• the exact meaning depends on context

In this sentence:

• Nasza firma is clearly our company
• nowego pracownika is most naturally a new employee

Polish usually lets context do the work that articles do in English.

It can correspond to both looks for and is looking for in English.

Polish does not make the same present simple vs. present continuous distinction that English does.

So:

• firma szuka pracownika can mean
  • the company looks for an employee in a general sense, or more naturally
  • the company is looking for an employee

In this sentence, is looking for is usually the best English translation.

Yes, Polish word order is more flexible than English word order, because case endings show grammatical relationships.

The neutral order here is very natural:

• Nasza firma szuka nowego pracownika do biura, ale nie każdy współpracownik lubi zmiany.

But other orders are possible for emphasis, for example:

• Nowego pracownika do biura szuka nasza firma...
• Ale zmian nie każdy współpracownik lubi.

Those versions are more marked and sound more emphatic or stylistically shaped.

For learners, the original sentence is the safest and most neutral pattern to use.