التكاليف منخفضة بالفعل.

Because this is a nominal sentence in Arabic. In the present tense, Arabic usually does not use a verb equivalent to is/are.

So:

• التكاليف منخفضة = The costs are low

There is no present-tense to be written here. This is completely normal in Arabic.

التكاليف means the costs or the expenses.

A few useful points:

• الـ = the
• تكاليف is the plural of تكلفة = cost
• So التكاليف is a definite plural noun

It is the subject/topic of the sentence.

This is one of the most important grammar points in Arabic.

التكاليف is a non-human plural, and in Modern Standard Arabic, non-human plurals usually take feminine singular agreement.

So although التكاليف means costs and is plural, the adjective comes as feminine singular:

• التكاليف منخفضة

Not normally:

• التكاليف منخفضون or منخفضات in this kind of standard structure

This is very common in Arabic:

• الأسعار مرتفعة = The prices are high
• الكتب جديدة = The books are new

Even though books and prices are plural, the adjective is feminine singular.

It is feminine because it is agreeing with a non-human plural noun, and Arabic treats that type of plural as grammatically feminine singular for agreement in many contexts.

The base adjective is:

• منخفض = low (masculine singular)

Here it becomes:

• منخفضة = feminine singular

That is the form required after التكاليف.

بالفعل often means:

• indeed
• actually
• in fact
• already

In this sentence, the most natural meaning is something like:

• The costs are indeed low
• The costs are already low
• The costs are actually low

The exact nuance depends on context.

For example:

• If someone doubted it, بالفعل may mean indeed / actually
• If there is a sense of timing or change, it may mean already

In Arabic, adverbial expressions like بالفعل are often placed after the main statement.

So:

• التكاليف منخفضة بالفعل

is a very natural way to say:

• The costs are low بالفعل
• in smoother English: The costs are indeed/already low

You may also see adverbs in other positions depending on style and emphasis, but the final position here is very normal.

Here, منخفضة is functioning as the predicate adjective of the sentence.

It describes the subject:

• التكاليف = the costs
• منخفضة = low

So the structure is:

• subject
  • predicate

In traditional Arabic grammar terms, this is:

• التكاليف = مبتدأ
• منخفضة = خبر

A common pronunciation is:

at-takālīfu munkhafiḍatun bil-fiʿl

In normal pause, the final case endings are often not pronounced, so you will often hear something closer to:

at-takālīf munkhafiḍa bil-fiʿl

A few pronunciation notes:

• الـ before ت is assimilated, so التكاليف sounds like at-takālīf, not al-takālīf
• خ is a throaty sound, like the ch in German Bach
• ض is an emphatic consonant, deeper/heavier than plain d

They are:

• تكلفة = cost
• تكاليف = costs
• منخفض = low
• بالفعل = indeed / actually / already

So the sentence is built very economically:

• التكاليف = the costs
• منخفضة = low
• بالفعل = indeed/already

Yes. Depending on context, التكاليف can be translated as:

• costs
• expenses
• sometimes expenditures

And بالفعل can mean already.

So possible translations include:

• The costs are already low
• The expenses are already low
• The costs are indeed low

The best choice depends on the situation, but the Arabic structure stays the same.