التحكم في الجهاز مهم.

التحكم means control or controlling. It is a verbal noun (called maṣdar in Arabic) from the verb تحكَّمَ (to control).

So in this sentence, Arabic is using a noun-like form, not a finite verb. A very literal breakdown is:

التحكم في الجهاز مهم
Controlling the device is important / Control of the device is important

This is very common in Arabic: a verbal noun can act like the subject of a sentence, much like controlling in English.

The الـ is the definite article, like the in English.

So تحكم = control / controlling
التحكم = the control / controlling

In English, we often do not think of controlling as definite, but Arabic often uses الـ with verbal nouns in general statements. Here, التحكم refers to the concept or act of control in a general, understood way.

So this sounds natural in Arabic even though the English translation may simply be Controlling the device is important.

في usually means in, but with some nouns and verbal nouns it can express something like over, with, or regarding, depending on context.

Here, التحكم في الجهاز means something like:

• control of the device
• controlling the device
• more literally, control in the device

Arabic often uses a preposition where English might use of or no preposition at all.

If you simply put the nouns next to each other as an iḍāfa construction, the meaning would change or sound less natural.
So التحكم في الجهاز is the standard way to say control of / over the device in this context.

الجهاز means the device. The الـ makes it definite.

So:

• جهاز = a device
• الجهاز = the device

In this sentence, the speaker is referring to a specific device or to the device as a known thing in context. That is why الجهاز is definite.

Yes. After a preposition like في, the following noun is in the genitive case.

So الجهاز is majrūr because it follows في.

In fully vocalized Arabic, you would see:

التَّحَكُّمُ فِي الجِهَازِ مُهِمٌّ

Notice the ending -i sound on الجهازِ. In normal everyday writing, short vowels are usually not written, so you just see الجهاز.

It is masculine because التحكم is treated as a masculine noun.

Even though التحكم refers to an action, grammatically it is still a noun, and nouns in Arabic have grammatical gender. تحكم is masculine, so the adjective/predicate is also masculine:

• التحكم ... مهم
• not مهمة

If the subject were a feminine noun, then the predicate would usually be feminine too.

There is no verb in this sentence. This is a nominal sentence in Arabic.

Structure:

• التحكم في الجهاز = the subject/topic
• مهم = the predicate/comment

So the sentence is basically:

• Controlling the device = important

In Arabic, present-tense to be is usually omitted. So Arabic says:

التحكم في الجهاز مهم

where English needs:

Controlling the device is important

Yes, that is a reasonable translation depending on context.

Possible natural translations include:

• Controlling the device is important.
• Control of the device is important.
• Device control is important.

The exact English wording depends on what sounds most natural in the situation. The Arabic sentence itself is broad enough to allow these slightly different English versions.

Yes, the ل in الـ is pronounced here, because ت in تحكم is not one of the sun letters.

So it is pronounced roughly:

at-taḥakkum? No—that would happen only with a sun letter.

The correct pronunciation is more like:

al-taḥakkum

More fully with vowels: at-taḥakum is incorrect here.
al-taḥakkum is correct.

The ح is a deep voiceless throat sound that does not exist in English, and كّ is doubled, so the k is held slightly longer.

In fully vocalized MSA, the sentence would be:

التَّحَكُّمُ فِي الجِهَازِ مُهِمٌّ

The endings are:

• التَّحَكُّمُ → -u because it is the subject of the nominal sentence
• فِي → preposition
• الجِهَازِ → -i because it follows a preposition
• مُهِمٌّ → -un because it is the predicate and is indefinite

In normal unvowelled writing, these endings are usually omitted, so learners have to infer them from grammar.

Yes, you can say السيطرة على الجهاز مهمة. It also means something like controlling the device is important or control over the device is important.

But there is a slight difference in nuance:

• التحكم في الجهاز often sounds like operating, managing, or controlling a device in a practical or technical sense.
• السيطرة على الجهاز can sound more like dominating, having command over, or gaining control over something.

Also notice the different preposition:

• التحكم في
• السيطرة على

So both are possible, but التحكم في الجهاز is especially natural for technical or device-related contexts.