Kiedy stroję gitarę, zawsze najpierw słucham instrumentu.

Here kiedy means when or, more naturally in this kind of sentence, whenever.

So Kiedy stroję gitarę... is not about one specific moment only. It describes a repeated habit:

• Whenever I tune the guitar, ...

That is why the whole sentence feels general and habitual.

Stroję is the 1st person singular present tense of stroić.

• stroić = to tune
• stroję = I tune / I am tuning

The ending -ę tells you the subject is I.

Polish present tense often covers both English ideas:

• I tune the guitar
• I am tuning the guitar

The exact meaning depends on context.

Because gitara is the direct object of stroję, so it has to be in the accusative case.

For a feminine noun ending in -a, the accusative singular usually changes to -ę:

• gitara = nominative
• gitarę = accusative

So:

• stroję gitarę = I tune the guitar

Because the verb słuchać requires the genitive case, not the accusative.

That is something English speakers often have to memorize, because English just says listen to without changing the noun in this way.

So:

• instrument = nominative
• instrumentu = genitive

And therefore:

• słucham instrumentu = I listen to the instrument

In standard Polish, yes: słuchać normally takes the genitive.

Examples:

• słucham muzyki = I listen to music
• słucham radia = I listen to the radio
• słucham nauczyciela = I listen to the teacher

So słucham instrumentu follows a very common pattern.

This is an important distinction:

• słuchać = to listen → an active, intentional action
• słyszeć = to hear → simply perceiving sound

In this sentence, the person is deliberately paying attention to the guitar’s sound, so słuchać is the correct choice.

Compare:

• Słucham instrumentu = I am listening to the instrument
• Słyszę instrument = I hear the instrument

This is mostly a matter of style and perspective.

The speaker first mentions the specific object:

• gitarę

Then, in the second part, they refer to it more generally as:

• instrumentu = the instrument

That sounds natural and avoids repeating gitary immediately.

It also slightly emphasizes that when tuning, you listen carefully to the instrument as a sound-producing object, not just to a guitar as a named item.

• zawsze = always
• najpierw = first

They do different jobs:

• zawsze tells you this is a regular habit
• najpierw tells you the order of actions

So:

• zawsze najpierw słucham instrumentu = I always listen to the instrument first

Together they mean that listening comes first every time.

Yes, Polish word order is fairly flexible, but the version here is very natural.

Kiedy stroję gitarę, zawsze najpierw słucham instrumentu. sounds like a neutral, normal sentence.

You could move things around for emphasis, for example:

• Kiedy stroję gitarę, najpierw zawsze słucham instrumentu.
• Zawsze, kiedy stroję gitarę, najpierw słucham instrumentu.

These are possible, but they may sound more marked or place emphasis in a different spot. The original sentence is the most straightforward.

Because Kiedy stroję gitarę is a subordinate clause, and in Polish subordinate clauses are normally separated from the main clause by a comma.

So the structure is:

• Kiedy stroję gitarę = subordinate clause
• zawsze najpierw słucham instrumentu = main clause

That is why the comma is required.

Because Polish commonly uses the present tense for habitual actions.

So Kiedy stroję gitarę... means:

• When/whenever I tune the guitar...

not necessarily right now, but as a general routine.

This is similar to English in sentences like:

• When I cook, I always taste the food first.

It is a general truth about what the speaker does.