Pokrivenost mrežom je važna.

Mrežom is the instrumental singular of mreža (network).

In the phrase pokrivenost mrežom, Croatian uses the instrumental to express the idea of being covered by something or with something. So the structure is:

• pokrivenost = coverage
• mrežom = by/with network

Literally, it is something like coverage with a network or coverage by the network.

This is a common pattern with nouns related to covering or filling:

• prekriven snijegom = covered with snow
• napunjen vodom = filled with water

So pokrivenost mrežom is grammatically natural in Croatian.

It is the instrumental case, singular.

The noun is:

• nominative: mreža
• genitive: mreže
• dative/locative: mreži
• accusative: mrežu
• vocative: mrežo
• instrumental: mrežom

In this sentence, instrumental is used because the noun expresses what provides the coverage.

Because važna agrees with pokrivenost, and pokrivenost is a feminine noun.

In Croatian, adjectives must agree with the noun they describe in:

• gender
• number
• case

Here:

• pokrivenost = feminine singular
• therefore važna = feminine singular

Compare:

• signal je važan = the signal is important (masculine)
• pokrivenost je važna = coverage is important (feminine)
• područje je važno = the area is important (neuter)

A very useful clue is the ending -ost.

Many Croatian nouns ending in -ost are feminine:

• važnost = importance
• mogućnost = possibility
• sigurnost = safety/security
• pokrivenost = coverage

So when you see a noun in -ost, it is very often feminine, and adjectives with it will usually take feminine forms.

Je is the 3rd person singular present of the verb biti (to be).

So the sentence structure is:

• Pokrivenost mrežom = network coverage
• je = is
• važna = important

Croatian often uses je just like English uses is in simple statements.

In a normal full sentence like this, no—you usually keep it.

So:

• Pokrivenost mrežom je važna. = correct

Leaving out je would sound incomplete in standard Croatian:

• Pokrivenost mrežom važna. = not standard as a normal sentence

In headlines, notes, or very compressed style, verbs may sometimes be omitted, but for normal speaking and writing, keep je.

Yes, Croatian word order is more flexible than English, but the original order is the most neutral.

Neutral:

• Pokrivenost mrežom je važna.

Other possible orders:

• Važna je pokrivenost mrežom. = puts more emphasis on important
• Je važna pokrivenost mrežom? = possible in some contexts, but usually you would ask a question differently

Although word order can change, the clitic je often has special placement rules and usually appears early in the sentence, often in the second position area. So word order is flexible, but not completely free.

Because the adjective does not agree with the whole English idea network coverage as a unit in the English sense. It agrees with the Croatian head noun, which is pokrivenost.

The grammatical core of the phrase is:

• pokrivenost = coverage

And pokrivenost is feminine, so:

• važna, not važan

This is important for English speakers because Croatian agreement depends on the actual Croatian noun, not on how the phrase feels in English.

No, there are other ways depending on meaning and style.

For example:

• pokrivenost mreže would mean something different, more like the coverage of the network or the network’s coverage, depending on context
• signal je važan = the signal is important
• dobra pokrivenost signalom = good signal coverage
• pokrivenost mobilnom mrežom = coverage by a mobile network

So pokrivenost mrežom is natural, but Croatian may choose different nouns or cases depending on exactly what is being emphasized.

It comes from the idea of covering.

Related forms:

• pokriti = to cover
• pokriven = covered
• pokrivenost = coverage / coveredness

The suffix -ost often turns an adjective or participle-based idea into an abstract noun:

• pokriven → pokrivenost

So pokrivenost is an abstract noun meaning the state or quality of being covered.

A rough pronunciation guide:

• mrežom ≈ MREH-zhom

Notes:

• mr at the start is pronounced together; Croatian allows consonant clusters that may feel unusual to English speakers
• ž sounds like the s in measure or the g in genre
• the o is a clear short vowel, not a diphthong like in many English accents

So:

• mreža ≈ MREH-zha
• mrežom ≈ MREH-zhom

Not really in the way English learners often expect.

Croatian does not use articles like the or a/an. So:

• Pokrivenost mrežom je važna.

could mean:

• Network coverage is important
• The network coverage is important

The exact interpretation depends on context.

English speakers often look for an article-based distinction, but Croatian usually leaves that to context.

You could, but it would not mean exactly the same thing.

• Pokrivenost mrežom = coverage by/with the network
• Pokrivenost mreže = the coverage of the network

The first uses instrumental and focuses on what provides the coverage. The second uses genitive and treats network as a possessor or defining noun.

In practice, both may appear in real language, but they highlight the relationship differently. In your sentence, mrežom is the intended structure.