Kabel od zvučnika je kratak, pa sjedimo bliže stolu.

Because od is a preposition meaning from / of, and it requires the genitive case.

• dictionary form: zvučnik
• after od: zvučnika

So kabel od zvučnika means the cable from the speaker or the speaker’s cable, depending on context.

Yes, but the nuance is a little different.

• zvučnički kabel = speaker cable as a type of cable
• kabel od zvučnika = the cable from the speaker / attached to the speaker

In many real-life situations, both are possible, but kabel od zvučnika sounds more like a specific cable belonging to that speaker.

Because after je Croatian normally uses the short form of the masculine singular adjective in this kind of predicate:

• Kabel je kratak. = The cable is short.

Before a noun, you would more often see the longer form:

• kratki kabel = a short cable

Also, the adjective has to agree with kabel, which is masculine singular.

Je is the 3rd person singular present form of biti = to be.

So:

• kabel je kratak = the cable is short

In standard Croatian, you normally keep je in sentences like this. English speakers sometimes expect it to disappear because some other Slavic languages omit to be in the present tense, but Croatian does not.

Croatian does not have articles like a and the.

So nouns like zvučnika and stolu do not need separate words for the. Whether something is definite or indefinite usually comes from:

• context
• word order
• demonstratives such as ovaj, taj, onaj when needed

So the sentence can naturally mean the speaker and the table even though no article appears.

Because Croatian usually leaves out subject pronouns when the verb ending already shows who the subject is.

• sjedimo = we sit / we are sitting

The ending -mo already tells you it means we.

You can add mi if you want emphasis or contrast:

• Mi sjedimo bliže stolu. = We’re the ones sitting closer to the table.

Because sjediti and sjesti are different verbs.

• sjediti = to sit / to be sitting
• sjesti = to sit down

Here the sentence describes an ongoing position or situation, so sjedimo from sjediti is the right choice.

Compare:

• Sjedimo bliže stolu. = We are sitting closer to the table.
• Sjednemo bliže stolu. = We sit down closer to the table.

Here pa connects the two clauses and gives a result sense, like:

• so
• and so
• therefore

So the structure is basically:

• The speaker cable is short, so we sit closer to the table.

Pa is very common and natural in everyday Croatian. It is often less formal than words like stoga or zato.

Because bliže is the comparative adverb meaning closer.

It modifies the verb sjedimo, not the noun stol.

• blizu = near
• bliže = nearer / closer

So:

• sjedimo blizu stola = we sit near the table
• sjedimo bliže stolu = we sit closer to the table

If you used bliži, that would be an adjective, not the adverb needed here.

Because after bliže, Croatian often uses the dative case.

• dictionary form: stol
• dative singular: stolu

So:

• bliže stolu = closer to the table

English uses the separate word to, but Croatian can express that relationship through the case ending itself.

Because Croatian often uses case endings where English uses prepositions.

In bliže stolu, the idea of to the table is built into stolu, which is in the dative.

So Croatian does not need a separate word exactly matching English to here.

Not completely. Croatian word order is fairly flexible, but this sentence uses a very natural, neutral order.

• Kabel od zvučnika je kratak, pa sjedimo bliže stolu.

One important point is that je is a clitic, and clitics usually want to stand near the second position in their clause. That is one reason je appears where it does.

You can move things around for emphasis, but the given version is the most straightforward and natural for everyday use.