Kad god pečem meso, nosim kecelju.

Yes. Kad god means whenever or every time that.

• Kad pečem meso... = When I roast meat...
• Kad god pečem meso... = Whenever I roast meat... / Every time I roast meat...

So god adds the idea of repetition or generality. It makes the sentence sound more like a habit, not just one specific occasion.

In Serbian, the present tense is very commonly used for habitual or repeated actions, just like in English:

• Whenever I roast meat, I wear an apron.

So:

• pečem = I roast / I am roasting
• nosim = I wear / I am wearing / I carry, depending on context

Here the meaning is habitual: Whenever I roast meat, I wear an apron.

Because Serbian often drops subject pronouns when they are already clear from the verb form.

Both verbs clearly show first person singular:

• pečem = I roast
• nosim = I wear

So ja is not necessary. You could say:

• Kad god ja pečem meso, nosim kecelju.

But that usually adds emphasis, something like Whenever I roast meat...

The neutral, normal version is without ja.

Because peći is the infinitive, meaning to roast / to bake, while pečem is the 1st person singular present tense: I roast / I bake.

This verb changes quite a lot in conjugation, so it may look irregular to an English speaker:

• peći = to roast, to bake
• pečem = I roast / bake
• pečeš = you roast / bake
• peče = he/she/it roasts / bakes

So this is just the normal conjugated form, even though it does not look very similar to the infinitive.

Good question. Meso is the direct object, so it is in the accusative case. But for many neuter singular nouns, the nominative and accusative forms are the same.

So:

• nominative: meso = meat
• accusative: meso = meat

That is why you do not see any change here.

Because kecelja is a feminine noun, and here it is the direct object of nosim (I wear), so it must be in the accusative singular.

• nominative: kecelja = apron
• accusative: kecelju = apron

This is a very common pattern for feminine nouns ending in -a:

• knjiga → knjigu
• torba → torbu
• kecelja → kecelju

Both are imperfective verbs here, which is exactly what Serbian normally uses for habitual, repeated, ongoing, or general actions.

• peći / pečem = imperfective
• nositi / nosim = imperfective

Since the sentence describes a repeated habit, the imperfective is the natural choice.

If you used a perfective verb, it would usually point more to a completed single event, which does not fit as well with kad god.

Yes, you can. It would still be grammatical and natural.

But there is a slight difference in emphasis:

• Kad pečem meso, nosim kecelju. = When I roast meat, I wear an apron.
• Kad god pečem meso, nosim kecelju. = Whenever I roast meat, I wear an apron.

The version with god more clearly emphasizes every time.

Because the sentence begins with a subordinate clause:

• Kad god pečem meso = whenever I roast meat

Then comes the main clause:

• nosim kecelju = I wear an apron

In Serbian, it is standard to separate these clauses with a comma:

• Kad god pečem meso, nosim kecelju.

This is similar to English punctuation in sentences like:

• Whenever I roast meat, I wear an apron.

It can mean both, depending on context. The verb nositi is broad.

Common meanings include:

• to wear clothes or accessories
• to carry or to bring

Here, because the object is kecelju (an apron), the meaning is clearly wear:

• nosim kecelju = I wear an apron

Here meso is singular, but it often works like an uncountable mass noun, similar to English meat.

So:

• pečem meso = I’m roasting meat

You are not talking about a countable item like one meat / two meats. You are talking about the substance in general.

That is why meso is the natural form here.

Yes, Serbian word order is fairly flexible, though some versions sound more natural than others.

The given sentence is very natural:

• Kad god pečem meso, nosim kecelju.

You could also hear:

• Nosim kecelju kad god pečem meso.

That still means the same thing. The difference is mostly in focus:

• clause first: sets the situation first
• main statement first: puts a little more focus on nosim kecelju

So the original version is a very normal, neutral way to say it.