الصيانة مهمة للغاية.

A careful pronunciation is:

aṣ-ṣiyānah muhimmah lil-ghāyah

A few notes:

• الصيانة = aṣ-ṣiyānah
  • The ل of ال is not pronounced normally here, because ص is a sun letter.
  • So ال + صيانة sounds like aṣ-ṣiyānah, not al-ṣiyānah.
• مهمة = muhimmah
• للغاية is often pronounced lil-ghāyah in connected speech.

A natural full reading is:

aṣ-ṣiyānah muhimmah lil-ghāyah

Because Arabic often omits is/am/are in the present tense.

So:

• الصيانة مهمة للغاية literally looks like maintenance very-important to-the-utmost
• But in natural English, it means Maintenance is extremely important

This is called a nominal sentence in Arabic. In the present tense, Arabic usually does not use a separate verb for is.

If you wanted the past tense, then Arabic would use a verb, for example:

• كانت الصيانة مهمة للغاية
• Maintenance was extremely important

This is very common in Arabic.

• الصيانة = the maintenance / maintenance
• مهمة = important

In this kind of sentence, the first part is the subject and the second part is the predicate. The predicate is often indefinite.

So:

• الصيانة = the topic being talked about
• مهمة = what is being said about it

This is normal Arabic structure.

If both words were definite:

• الصيانة المهمة

that would usually mean the important maintenance, not maintenance is important.

Because it describes الصيانة, and adjectives in Arabic must agree with the noun they describe.

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

• مهم = important (masculine)
• مهمة = important (feminine)

Since الصيانة is feminine, Arabic says:

• الصيانة مهمة

not

• الصيانة مهم

Yes, الصيانة is treated as feminine.

One easy clue is the ending ـة in related forms, but here the word ends with ة only in pronunciation history? Let's look more carefully:

• The written form is الصيانة
• It does not end with ة, but it is still a feminine noun

In Arabic, not all feminine nouns have ـة, and some nouns are simply feminine by usage. Also, many abstract nouns are feminine.

So the best approach is:

• learn the noun with its gender
• notice agreement in real sentences

In this sentence, the feminine adjective مهمة confirms that الصيانة is feminine.

للغاية means extremely, to a great extent, or literally something like to the utmost / to the limit.

Breakdown:

• لـ = to
• الغاية = the limit, the utmost end, the extreme

So للغاية is an idiomatic expression meaning:

• very
• extremely
• highly

In this sentence:

• مهمة للغاية = extremely important

Yes, absolutely.

You can say:

• الصيانة مهمة جداً

This also means Maintenance is very important.

The difference is mostly one of style:

• جداً = very common, simple, everyday very
• للغاية = a bit more formal or emphatic, often translated as extremely

So both are correct, but للغاية sounds a little stronger or more formal.

Here it functions like an adjective used as the predicate of the sentence.

So in:

• الصيانة مهمة

مهمة means important.

However, you may also know مهمة as a noun meaning task or mission in other contexts. Arabic often has words that can function differently depending on the sentence.

Here the meaning is clearly adjectival because it describes الصيانة.

Because the middle consonant is written with a shadda:

• مُهِمَّة

That means the m sound is doubled:

• mu-him-mah

not just

• mu-hi-mah

This comes from the underlying adjective pattern. In practice, just remember that مهم and مهمة are pronounced with a doubled m sound.

In fully vowelled formal Arabic, it would be:

• الصيانةُ مهمّةٌ للغايةِ

Here is why:

• الصيانةُ: nominative, because it is the subject of the nominal sentence
• مهمّةٌ: nominative, because it is the predicate
• للغايةِ: genitive after the preposition لـ

In normal everyday reading, especially when pausing at the end of words, those short final vowels are usually not pronounced, so learners often hear:

• الصيانة مهمة للغاية

without the full endings.

Yes. This is a very normal and natural order.

Arabic nominal sentences often look like:

• subject + predicate

So here:

• الصيانة = subject
• مهمة للغاية = predicate

That makes the sentence straightforward and standard.

It usually means maintenance, upkeep, or servicing.

Depending on context, it may overlap a little with ideas like repair or technical servicing, but the most basic meaning is maintenance.

For example:

• قسم الصيانة = maintenance department
• أعمال الصيانة = maintenance work

If Arabic specifically wants to emphasize repair, other words may be used depending on context.

Yes, that is often fine in natural English, depending on how strong you want the translation to sound.

• للغاية is stronger than plain very
• So the most exact translation is something like extremely or very much

But in smooth English, people may still say:

• Maintenance is very important

If you want to preserve the emphasis more clearly, use:

• Maintenance is extremely important
• Maintenance is highly important

The first is the most natural English choice.