لن نستعمل شبكة عامة أبدا.

لن is a particle used to negate an action in the future. In this sentence, it means will not.

So:

• لن نستعمل = we will not use

A key grammar point: لن is followed by a verb in the present tense form but puts it into a subjunctive meaning/environment.

Because the sentence is talking about something that will not happen, Arabic uses:

• لن
  • present-tense verb

So even though the English translation uses will not use, Arabic does not use a separate future verb form here. Instead:

• نستعمل literally looks like a present-tense form: we use
• لن نستعمل means we will not use

The prefix نـ on نستعمل tells you the subject is we.

نستعمل means we use or we employ.

Yes, it is very close in meaning to نستخدم in many contexts. Both can often mean to use. In Modern Standard Arabic:

• استعمل = to use, employ
• استخدم = to use

In many everyday contexts, the difference is small or not important. In this sentence, لن نستعمل simply means we will not use.

Because the sentence is saying a public network, not the public network.

• شبكة عامة = a public network
• الشبكة العامة = the public network

Arabic often leaves nouns indefinite when English would use a/an.

So:

• شبكة = a network
• عامة = public

Together: شبكة عامة = a public network

Because عامة is an adjective describing شبكة, and adjectives in Arabic must agree with the noun they describe.

شبكة is a feminine singular noun, so the adjective must also be feminine singular:

• شبكة = network
• عامة = public (feminine singular form)

If the noun were masculine, the adjective would usually be masculine too.

In Arabic, adjectives normally come after the noun they describe.

So:

• شبكة عامة literally = network public
• natural English = public network

This is one of the most basic word-order differences between Arabic and English.

In this sentence, أبدا means ever or at all, and it strengthens the negation.

So:

• لن نستعمل شبكة عامة = We will not use a public network
• لن نستعمل شبكة عامة أبدا = We will never use a public network / We will not use a public network at all

With negative sentences, أبدا often gives the sense of never.

That is a very natural position for it. In Arabic, words like أبدا often come toward the end to emphasize the whole negative statement.

So the sentence structure is:

• لن = future negation
• نستعمل = we use
• شبكة عامة = a public network
• أبدا = ever / at all / never

Putting أبدا at the end gives strong final emphasis: never / not at all.

Both are good ways to understand it.

A more word-for-word breakdown is:

• لن = will not
• نستعمل = we use
• شبكة عامة = a public network
• أبدا = ever / at all / never

So literally it is something like:

• We will not use a public network ever

But in natural English, you would usually say:

• We will never use a public network

In full formal grammar, yes, there would be case endings, but they are usually not written in normal Arabic texts.

Fully vocalized, it could be read approximately as:

• لَنْ نَسْتَعْمِلَ شَبَكَةً عَامَّةً أَبَدًا

A few points:

• نستعملَ takes a final fatḥa because لن puts the present verb in the subjunctive
• شبكةً is indefinite and functions as the object
• عامةً agrees with شبكةً
• أبدًا is commonly written with tanwīn fatḥ

In ordinary writing, these endings are usually omitted, so you see:

• لن نستعمل شبكة عامة أبدا

Not with the same meaning.

• لا نستعمل شبكة عامة = we do not use a public network / we are not using a public network
  This does not clearly mean future.
• سوف نستعمل = we will use
• لن نستعمل = we will not use

So if you want a clear future negative, لن is the standard choice.

It is a verbal sentence, because it starts with a verb phrase:

• لن نستعمل

More precisely, it begins with a negation particle plus a present-tense verb.

Arabic often has two broad sentence types:

• verbal sentence: starts with a verb
• nominal sentence: starts with a noun

This one is verbal because the core action نستعمل comes right away after لن.