الممارسة مهمة.

In careful MSA with case endings, it is:

al-mumārasatu muhimmatun

In normal pause pronunciation, you will often hear:

al-mumārasah muhimmah

A few helpful notes:

• الممارسة = al-mumārasah
• مهمة = muhimmah
• The ة at the end is usually heard as -ah in pause.
• The مّ in مهمّة is doubled, because there is a shadda on it.

Because Arabic often does not use a present-tense form of to be.

So a sentence like:

الممارسة مهمة

literally looks like:

practice important

but it naturally means:

Practice is important.

This is called a nominal sentence in Arabic. In the present tense, Arabic usually just puts the subject and predicate next to each other.

Yes. It is a complete and very normal Arabic sentence.

Its two parts are:

• الممارسة = the subject
• مهمة = the predicate/adjectival description

So Arabic does not need an extra word like is here for the sentence to be complete.

Because that is the normal structure here.

Arabic commonly forms this kind of sentence as:

subject + predicate

So:

• الممارسة = the thing being talked about
• مهمة = what is being said about it

Also, Arabic adjectives normally come after the noun they describe. Here مهمة is functioning as the predicate adjective: important.

Because الممارسة is feminine, and the adjective agrees with it.

In Arabic, adjectives usually match the noun in:

• gender
• number
• definiteness (when they are attributive adjectives)

Here الممارسة is a feminine singular noun, so the adjective appears in the feminine singular form:

• masculine: مهم
• feminine: مهمة

The ة at the end is the usual feminine ending.

Because مهمة here is not the important; it is simply important.

So:

• الممارسة = the practice / practice
• مهمة = important

This is normal in this kind of sentence.

A very useful contrast:

• الممارسة مهمة = Practice is important
• الممارسة المهمة = the important practice

The second one is not a full sentence. It is just a noun phrase.

الممارسة is a verbal noun (also called a maṣdar) from the verb مارس.

So it refers to:

• practicing
• the act of practice
• practice as an activity

That is why it works well in a sentence like this. It names the activity itself.

The fully vocalized form is:

الممارسةُ مهمّةٌ

The ending -u on الممارسةُ and -un on مهمّةٌ show the nominative case.

In a basic nominal sentence like this, both parts are nominative:

• الممارسةُ
• مهمّةٌ

In everyday writing, these short vowel endings are usually omitted.

That letter is called tāʾ marbūṭa.

It usually marks a feminine noun or adjective.

So:

• ممارسة is feminine
• مهمة is feminine

In pronunciation:

• in pause, it usually sounds like -ah
• when case endings are pronounced, it is heard as -at before the ending, as in muhimmatun

Usually, الممارسة مهمة is the most straightforward order.

You can sometimes move parts around in Arabic for style or emphasis, but for a learner, the normal and safest pattern is:

subject + predicate

So this sentence is the standard way to say it.

Often yes, but the nuance is worth noting.

الممارسة usually suggests:

• the act of practicing
• carrying out something repeatedly
• practical engagement in something

Depending on context, Arabic might also use words like التدريب for training or drill.

So الممارسة is a very natural word here, but like many words, its exact feel depends on context.