خمسة ليترات كفاية.

Yes. In Levantine Arabic, the present-tense verb to be is usually omitted.

So the sentence is literally:

five liters enough

But in natural English, that becomes:

Five liters is enough / Five liters are enough

Both English versions express the same idea.

Because the singular noun is ليتر (liter), and it is normally treated as masculine.

With numbers 3–10, Arabic uses the opposite-gender form of the number:

• with a masculine noun: خمسة
• with a feminine noun: خمس

So خمسة ليترات is the expected form.

A common point of confusion is that ليترات ends in -ات, but that does not mean the noun is feminine for number agreement. The rule is based on the gender of the singular noun, ليتر.

Because after numbers 3–10, the counted noun is normally plural.

So:

• ليتر = liter
• ليترات = liters

That is why خمسة ليترات means five liters.

In formal Arabic, this construction also involves case endings, but in Levantine those endings are not pronounced, so learners just need to focus on the basic pattern: number + plural noun.

Because the phrase is talking about an indefinite quantity: five liters, not the five liters.

So:

• خمسة ليترات = five liters
• الخمسة ليترات = the five liters

Without ال, it is just a general amount.

كفاية means enough or sufficient.

In this sentence, it works as the predicate of the sentence:

• خمسة ليترات = five liters
• كفاية = enough

So the whole sentence means that this amount is sufficient.

In everyday Levantine, كفاية is a very common word in this kind of sentence.

Because كفاية is a very common colloquial Levantine way to say enough.

A learner who knows more formal Arabic may expect كافية, which is the more standard adjective-like form. In fact, a more formal version could be:

خمسة لترات كافية

But in everyday Levantine, كفاية is extremely natural and common.

So the difference is mainly:

• كفاية = more colloquial, everyday
• كافية = more formal / more standard-sounding

A rough pronunciation is:

khamse liitraat kfaaye

You may also hear something closer to:

khamse liitraat kifaaye

A few quick notes:

• kh is like the sound in Scottish loch or German Bach
• لي has a long ee sound
• كفاية may sound a bit compressed in fast speech

So if you say something close to khamse liitraat kfaaye, you will be understood.

No. ليترات is a common colloquial plural, especially in everyday speech and informal writing.

You may also see:

لترات

especially in more standard-style writing.

Both refer to liters. For a learner of Levantine, ليتر / ليترات is a very useful everyday pair to know.

It is definitely colloquial, and it sounds very natural in Levantine. It would also be widely understood in much of the Arabic-speaking world because both ليتر and كفاية are very common words.

A more formal / Standard Arabic version would be something like:

خمسة لترات كافية
or
خمسة لترات تكفي

So the sentence you were given is the kind of thing you would easily hear in conversation.

Yes, Arabic word order is somewhat flexible, but خمسة ليترات كفاية is a very natural, neutral way to say it.

The basic idea is:

• first say the amount: خمسة ليترات
• then say the comment about it: كفاية

That makes the sentence feel straightforward and conversational.

Other orders are possible in some contexts for emphasis, but the version you have is the best one to learn first.