Po badaniu w gabinecie lekarz pokazuje mi wynik i mówi, że po szczepieniu mogę jutro wrócić do pracy.

Polish does not have articles. So nouns like lekarz, gabinet, and wynik can mean a doctor / the doctor, an office / the office, a result / the result depending on context.

In this sentence, the context makes them feel definite in English, so you translate them as the doctor, the office/consulting room, and the result.

If Polish wants to be extra specific, it can use words like ten = this/the, but that is not required the way it is in English.

Because po meaning after normally takes the locative case.

So:

• badanie → po badaniu
• szczepienie → po szczepieniu

This is a very common pattern:

• po pracy = after work
• po obiedzie = after lunch
• po spotkaniu = after the meeting

So if you see po in the sense of after, you should often expect the locative.

Not here. Gabinet is a false friend for English speakers.

In this sentence, gabinet means something like:

• doctor’s office
• consulting room
• medical office

So w gabinecie means in the doctor’s office / in the consulting room, not in the cabinet.

Because w meaning in or at takes the locative case when it describes location.

So:

• base form: gabinet
• after w for location: w gabinecie

Compare:

• w gabinecie = in the office
• do gabinetu = to the office / into the office

That is an important contrast:

• w
  • locative = location
• do
  • genitive = motion toward

Because pokazywać komuś coś means to show someone something.

That gives you:

• komu? = to whom? → mi = to me, in the dative
• co? = what? → wynik, the thing being shown

So:

• mi = indirect object, to me
• wynik = direct object, the result

mnie can also be a form of I/me, but mi is the normal short unstressed dative form here. Mnie is usually used for emphasis or after prepositions.

It is in the accusative case, but wynik is a masculine inanimate noun, and in the singular its accusative form is the same as its nominative form.

So grammatically:

• nominative: wynik
• accusative: wynik

That is why you do not see a visible change.

Compare that with a masculine animate noun:

• lekarz = doctor
• widzę lekarza = I see the doctor

There, the accusative does look different.

Że means that and introduces a subordinate clause.

So:

• mówi, że... = he says that...

In standard Polish, you put a comma before że:

• mówi, że po szczepieniu mogę jutro wrócić do pracy

This is normal Polish punctuation.

Because wrócić is perfective, and here it fits the meaning better.

• wrócić = to return, to get back, one completed return
• wracać = to be returning / to return repeatedly / habitually

In this sentence, the doctor means a single future event:

• you can return to work tomorrow

So mogę jutro wrócić do pracy is the natural choice.

After móc + infinitive, Polish can use either aspect depending on meaning, but here the perfective verb is the best match.

Because wrócić do pracy is the normal pattern for return to work.

The preposition do takes the genitive case, so:

• praca → pracy

So:

• do pracy = to work / back to work

Compare:

• jestem w pracy = I am at work
• idę do pracy = I am going to work
• wracam do pracy = I am returning to work

They are in the present tense because the sentence is describing a scene as it happens, or using the narrative present.

So the idea is:

• After the examination, the doctor shows me the result and says...

Polish often uses the present tense like this when telling a story vividly or describing a typical situation.

If you wanted to describe one finished past event, you would usually say:

• lekarz pokazał mi wynik i powiedział...

Yes. Polish word order is fairly flexible because case endings show what each word is doing.

The original order is natural and neutral:

• Po badaniu w gabinecie lekarz pokazuje mi wynik i mówi...

It begins with the time/place setting, then gives the main action.

Other orders are possible, for example:

• Lekarz po badaniu w gabinecie pokazuje mi wynik i mówi...
• Lekarz pokazuje mi wynik po badaniu w gabinecie i mówi...
• Po szczepieniu mogę wrócić jutro do pracy
• Po szczepieniu mogę jutro wrócić do pracy

These versions may sound slightly different in emphasis, but the core meaning stays the same.